I’m dying of thirst. Can I start drinking seawater?

May 29, 2012 · Castaway Survival

Before, when I saw a castaway having a bad time, literally dying for a drink but surrounded by seawater, the message in films was always ‘whatever happens, never start drinking seawater. If you were to do so, perhaps you’d feel a bit better, a bit less thirsty, but it wouldn’t be long before you were dead. In films nobody explained the reason for this warning, but neither did anyone doubt it was true.

Let’s explain why.

Imagine that you’re drifting on a piece of wood in the middle of the ocean. Your mouth is dry. You are totally surrounded by seawater. The sea is the most amazing blue… Sometimes the sea seems to be a greenish colour and that’s because of the tiny bits of seaweed which make up the phytoplankton which is also green, as are all plants that perform photosynthesis… But then you can’t stand it anymore, you give in and start drinking sea water.

Seawater makes up 97.3 % of the Earth’s water so only 2.7% is fresh water. You convince yourself that there can’t be so much poison in the world, but there is.

Our kidneys are the filters that separate the waste material in the blood and this waste is then stored in the form of urine in the bladder, ready to be expulsed from the body. A kidney cannot make urine from a concentration of salts of more than 2%. Seawater is made up of approximately 3% salt, so if we drink it to quench our thirst the kidneys have to use existing water from our body in order to dilute the extra salt, which in turn makes us feel even thirstier.

This is due to the osmosis process where the kidneys can only generate urine which is less salty than the water we drink. Consequently, the body tends to urinate more to be able to eliminate the excess of salt but instead of elimination, the result is the formation of more salt as the urine obtained is always less salty than the original. The body would have to expulse more liquid than the amount drunk, which is impossible and that’s why the effect of drinking water from the sea is, paradoxically, dehydration.

Seawater contains three percent salt. This means that if we drink a litre our kidneys would need at least one and a half litres of fresh water to dilute all the salt, so this means that they would be forced to extract an extra half a litre from our body.

WHICH IS BEST, DIE OF THIRST OR DRINK SEAWATER?

This is the interesting part. In 1952 a Doctor named Alain Bombard made experiment called “Voluntary Castaway” and deliberately drifted across the Atlantic for 65 days in a dinghy with no provisions. He demonstrated that should you find yourself at high sea and it’s been a few days since it last rained, maybe it would be possible to drink small doses of seawater: Just one spoon of seawater at 20 minute intervals, drinking very slowly and letting the saliva in your mouth reduce the saline in the water you have swallowed. However it is known that Dr. Bombard had cheated by sneaking provisions aboard.

Luckily, our clients voluntary castaways will hardly face water shortage on our desert islands, because on most of them they will find coconut tress 🙂

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{ 105 comments… read them below or add one }

MaRvic C. BriÑan September 15, 2012 at 1:17 pm

nyc one!

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Peter Jhon Campaner September 24, 2012 at 8:42 am

ahmp

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Somebody April 19, 2013 at 12:00 pm

its Fab!!!!!!

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Alvaro Cerezo November 1, 2019 at 12:27 am

🙂

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Somebody April 19, 2013 at 12:02 pm

its nice! it helped me in my project. ThanQ very very very very very very very very very mmmmmmmmmuuuuuuuucccccccchhhhhhhhh !!!!!!!!!!!!!!!

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Alvaro Cerezo April 29, 2013 at 9:44 pm

You are welcome!

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Wiki June 13, 2013 at 9:15 pm
Andrew Whittaker June 4, 2014 at 11:53 pm

Something everyone knew. but either way…interesting/…

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Alvaro Cerezo October 9, 2014 at 3:12 pm

Thanks! 🙂

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Ambrose October 1, 2016 at 12:20 am

I didn’t know why at least, never assume everyone knows!

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Alvaro Cerezo March 3, 2017 at 4:41 am

🙂

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Amardeep Singh July 11, 2014 at 4:17 pm

NICE ARTICLE

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Alvaro Cerezo October 9, 2014 at 3:13 pm

Thanks! 😀

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Chee Woon July 22, 2014 at 4:45 pm

Good article!!

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Alvaro Cerezo October 9, 2014 at 3:13 pm

Thanks 😀

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Raly Todorova August 3, 2014 at 10:15 am

So if you get shipwrecked in the middle of the Black Sea, where the salinity is ~1.7%, drinking the water won't have you dehydrated?

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Alvaro Cerezo April 19, 2015 at 1:26 pm

Yes. In the Black Sea you will probably have a little more chances to survive 🙂

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Mohammad Bilawal August 6, 2014 at 3:07 am

We can drink sea water from the bottom of the sea if we are a little further and we can store it in something,

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Alvaro Cerezo May 21, 2017 at 1:23 am

Sorry Mohammad. I could understand what you said.

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Alvaro Docastaway August 29, 2014 at 8:00 pm

Thanks Brett 🙂

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Alvaro Docastaway August 29, 2014 at 8:00 pm

Thanks Amardeep 🙂

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Alvaro Docastaway August 29, 2014 at 8:00 pm

Thanks Chee 🙂

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Alvaro Docastaway August 29, 2014 at 8:01 pm

Probably yes. Even more dehydrated if you get adrift in the dead sea 🙂

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Alvaro Docastaway August 29, 2014 at 8:03 pm

Sorry Mohammad. I could understand what you said.

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Mohammad Bilawal August 29, 2014 at 9:52 pm

Alvaro Docastaway You can drink the sea water if you go above the sea level like a little further from the starting of sea and store it in a bottle from the bottom of the sea as its pure from down side not the upward. I hope it helps bro 🙂

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Alvaro Cerezo May 21, 2017 at 1:25 am

I’m not sure if I understood it well. However thanks for the tip 🙂

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Georgianna October 3, 2014 at 5:32 pm

Hello! This post couldn’t be written any better!
Reading this post reminds me of my good old room mate! He always kept chatting
about this. I will forward this article to him.
Pretty sure he willl have a good read. Many thanks
for sharing!

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Alvaro Cerezo May 21, 2017 at 1:32 am

Thanks 🙂

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Pweety One October 8, 2014 at 11:54 pm

Thanks so much! This helped with the exam I am taking. Nice article by the way.

Kay kay!

~Bye!~

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Ninja Queen October 9, 2014 at 12:02 am

itz sorta hard trying to figure this out but now i kinda get it. Thanks

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that guy November 12, 2014 at 5:55 pm

thanks this site helped!

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Alvaro Cerezo February 9, 2015 at 4:51 pm

Thanks 🙂

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King Louis January 4, 2015 at 6:33 am

The color of the ocean is not due to reflecting the color of the sky, and the greenish color of shallower water is not due to algae or phytoplankton! Since the color of the ocean is not due to reflection, then why is the color of deep water blue and shallow water green? Research it!

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Alvaro Cerezo January 8, 2015 at 4:32 pm

Thanks for the tip. We will! 😉

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mike April 20, 2015 at 8:45 am

Really don’t know y ur saying shit if u dont even know why it happens. How do u know that’s not y its blue. And Wtf does it matter that’s not what the article was about just reminding u it about staying alive while stranded in the ocean which probably could have saved quite a few people if they would have know this information. Which apparently everyone knew according to the dick that left another stupid comment Sry Alvaro Cerezo can’t handle rude And ignorant people and there is an abundance of them on the internet. It was a very good article and u might have saved someone’s life by posting it.

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Alvaro Cerezo April 20, 2015 at 4:57 pm

Thanks so much for your compliments Mike.

King Louis wanted to correct me because I actually made a mistake by saying that the colour of the sea is blue because of the reflecting of the sky. Actually is not exactly true so I removed it from the post 🙂

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meme February 5, 2015 at 5:19 pm

Meme.

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Alvaro Cerezo April 19, 2015 at 1:11 pm

🙂

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ryan abubakar February 6, 2015 at 12:59 am

Great article… Very interesting and well written…cheers

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Alvaro Cerezo February 9, 2015 at 4:52 pm

Thanks 🙂

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Tp March 30, 2015 at 11:00 pm

This helped for an osmosis assignment I had. Thank you so much.

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Alvaro Cerezo April 5, 2015 at 8:35 am

I’m glad to hear that 😉

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RMF April 4, 2015 at 7:20 pm

You say “This is due to the osmosis process where the kidneys can only generate urine which is less salty than the water we drink.”

I would have thought that urine is MORE salty that the water we drink…

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Alvaro Cerezo April 5, 2015 at 8:35 am

Yes you are right.

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Megan McClure April 18, 2015 at 7:51 pm

Actually, the Black Sea water is Brackish, not saline. You could drink a lot more of this water, in fact it is on the borderline of thirst-quenching. 1.7% salt is close to the salt content of urine. It would be a roll of the dice to drink this water, but much less chance of dehydration than seawater.

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Megan McClure April 18, 2015 at 7:51 pm

Glad someone caught those errors!

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King Louis April 19, 2015 at 2:12 am

Megan McClure I forgot to ask him why the sky is blue! Maybe it's because it's reflecting the color of the ocean! Haha!

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imran April 19, 2015 at 12:09 pm

Your this article is very informative. I was just wondering can anyone tell me if there is any part of the world where the salt in the ocean is considerably low.

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Alvaro Cerezo April 19, 2015 at 1:08 pm

Thanks Imran

High concentrations are usually in the center of the ocean away from the mouths of rivers, which brings fresh water. At high latitudes, salinity is low. This can be attributed to lower evaporation rates (because is less shot and the water evaporated is normally from surface) and the melting of ice that dilutes seawater. To sum up, salinity is low where precipitation is greater than evaporation, mainly in coastal or equatorial regions.

On this map you will understand it better
http://bit.ly/1Egclak

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Alvaro Docastaway April 19, 2015 at 12:36 pm

Megan McClure Yes. You are right. In theory. in the Black Sea you will probably have little more chances to survive if you drink its water, but maybe it would be useless as the water you drink will be just to clean the salt. However, as you can see on the map below, if you are in the Romanian – Odessa part of the Black Sea, not far from mouths of rivers, you would probably be able to drink as much as you wanted, but with the risk of getting a very high blood pressure and of course a possible diarrhea 🙂 http://people.iarc.uaf.edu/~gleb/crdf_black_sea/s_04_0.png

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Mike Wolfinbarger April 20, 2015 at 7:24 am

Thanks man if u didn't say it I would have haha ignorance

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Alvaro Cerezo April 20, 2015 at 4:57 pm

😉

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Samson John April 26, 2015 at 2:14 pm

Megan McClure Who would get trapped for days in the black sea anyways?

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Konjengbam James October 29, 2015 at 3:02 am

good informations

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Steve Mann February 15, 2016 at 1:18 am

King Louis The sky is blue because of the Sun. Or rather the light from the sun. As the Sunlight approaches Earth, it appears blue. In the afternoon, as the sunlight is receding, it appears yellow. Look it up. 🙂

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Ann India March 25, 2016 at 10:03 am

great, now I know

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David Castaldo April 21, 2016 at 11:50 am

Steve Mann why is blue paint blue? Its because blue paint absorbs the non-blue colors of the light spectrum. Just like the ocean or the sky. This is how color is perceived.

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Nelson Cajetin Diego Alfonso June 3, 2016 at 11:27 am

King Louis No its beacuse of the gases

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Gurmeet Singh June 26, 2016 at 1:59 pm

Good article

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Fenton West July 24, 2016 at 4:43 pm

Stfu

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poop November 5, 2016 at 6:27 pm

I LIKE POOP

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Alvaro Cerezo March 3, 2017 at 4:26 am

We too 🙂

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Shanequuuaaaa November 7, 2016 at 2:44 am

This is really cool.

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Alvaro Cerezo March 3, 2017 at 4:26 am

🙂

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camping water bottle January 27, 2017 at 1:24 pm

If some one needs to be updated with most recent technologies afterward he must be visit this website
and be up to date everyday.

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Alvaro Cerezo May 21, 2017 at 1:05 am

🙂

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Head Baker April 13, 2017 at 6:38 pm

Muhammad

I am still confused on what you were saying

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MORE HOT FOOD April 25, 2017 at 9:27 am

Ding dong bookie

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Alvaro Cerezo May 21, 2017 at 1:20 am

😛

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Stuart April 27, 2017 at 1:14 pm

right so since your body needs salt, if you HAD drinking water, should you consume a small amount of sea water in tandem with fresh water?

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Alvaro Cerezo May 21, 2017 at 1:19 am

Sea water it seems to have a of good minerals. However, a person shouldn’t abuse of salt, as increases the blood pressure.

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Jesse May 17, 2017 at 12:28 pm

The Wikipedia page on Alain Bombard mentions of a German physician, Hannes Lindemann who said that and quote from Wikipedia

“Lindemann later claimed that Bombard had actually taken along fresh water and consumed it on the ocean, and that he had also been secretly provided further supplies during his voyage. Lindemann’s own observations about reactions to scarce fresh water supplies became the basis for the World Health Organisation’s navigation recommendations.”

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Alvaro Cerezo May 20, 2017 at 11:33 pm

Alain Bombard was a fascinanting man but his reputation wasnt the best 🙂

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Jesse May 17, 2017 at 12:30 pm

The Wikipedia page on Alain Bombard mentions of a German physician, Hannes Lindemann who said that, and quote from Wikipedia

“Lindemann later claimed that Bombard had actually taken along fresh water and consumed it on the ocean, and that he had also been secretly provided further supplies during his voyage. Lindemann’s own observations about reactions to scarce fresh water supplies became the basis for the World Health Organisation’s navigation recommendations.”

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Alvaro Cerezo May 21, 2017 at 1:04 am

Alain Bombard was a fascinanting man but his reputation wasn’t the best ?

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Pip August 6, 2017 at 5:07 am

In dire circumstances, you can re-hydrate your body with seawater enemas. Not the most pleasant way to get your H2O fix, but it works. Your lower/lowest intestine is not a fan of salt and will not let it pass your osmotic barrier..

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Alvaro Cerezo September 30, 2017 at 1:12 am

I think it can be risky. It is not probed that lower intestines are able to stop salt

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genius September 9, 2017 at 5:27 pm

The whales drink it. The turtles drink it. The fish drink it. The dolphins drink it. The penguins drink it. The polar bears drink it. The seals drink it. It doesn’t kill them. Every living thing in the ocean drinks it. So if I had to, I would drink ocean water.

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Alvaro Cerezo August 11, 2018 at 5:05 am

mmmm :/

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Russ June 13, 2019 at 3:21 pm

Actually, polar bears do not drink seawater, as it would kill them. Polar bears have adapted their kidneys and digestive system to survive for long periods of time off the water they get from eating meat. Whales and dolphins have specially developed kidneys that work differently than human kidneys. The reason humans don’t have similar kidneys to whales is that humans are bipedal land animals, so carrying around heavier, less-efficient kidneys specialized in filtering saline water, although a life-saving advantage in the extremely rare chance of becoming lost at sea, usually just makes us slower, weaker, and more prone to injury, which, in turn, would make us less likely to survive.

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Alvaro Cerezo June 24, 2019 at 8:25 pm

Thanks for the tip 🙂

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niruth October 30, 2017 at 3:06 pm

great job you are spreading knowledge !!

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Alvaro Cerezo August 11, 2018 at 5:04 am

Thanks 🙂

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niruth October 30, 2017 at 3:07 pm

best information!!!!!!!!!!

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Alvaro Cerezo August 11, 2018 at 5:04 am

Thanks 🙂

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shan November 6, 2017 at 8:25 pm

interesting about the “voluntary castaway” experiment!

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Alvaro Cerezo August 11, 2018 at 5:04 am

Yes 🙂

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Verse February 3, 2018 at 10:04 pm

I like how the doctor set out to prove if people could sustain life while drinking low amounts of saltwater without any provisions… but snuck the provisions. Wtf? He tried to prove an experiment, but instead proved to be an epic cheating, failure. Wudda dumbass!

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Alvaro Cerezo August 11, 2018 at 4:51 am

Do you mean Dr. Bombard?

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Kemal September 24, 2018 at 11:25 am

Dr. Alain Bombard may be a cheater, but what if human can actually survive by drinking seawater? How about the case of Aldi, a 19 years old boy who stranded at sea for 49 days? Basically, he is like the real life “Life of Phi”. It said that he drank seawater to survive. Maybe human are more adaptable than we thought (or theorised).

https://www.bbc.com/news/world-asia-45623130

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Russ June 13, 2019 at 3:39 pm

The link you provided doesn’t make the claim you said it stated. Research the young man’s story and you’ll find out that, because of the provisions on the boat when it broke anchor, he went 4 days without fresh water out of the 49 days he was adrift, and he basically was able to continue fishing and eating the fish he caught the entire time. Since the human body can survive 7-10 days without any water while fasting, and food also gives the body some usable water, Aldi’s story about drinking small amounts of seawater for four days doesn’t really prove anything about whether sea water will keep you alive any longer than no water.

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Alvaro Cerezo June 24, 2019 at 8:25 pm

You are right. i would personally recommend not to drink sea water at all.

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Alvaro Cerezo June 24, 2019 at 11:53 pm

Yes. The fact that Aldi said that he drank seawater really surprised me. I bet he might still have fresh drinking water in bottles. However I will confirm that in the next months as I will personally meet him in Indonesia.

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Pat December 13, 2018 at 5:02 am

What about alan bombard and Rene Quintín?

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Alvaro Cerezo June 24, 2019 at 8:42 pm

Honestly, Bombard experiement was a bit odd

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daddy kai January 16, 2019 at 11:11 am

HA GAY LOL

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daddy kai January 16, 2019 at 11:13 am

I like boys

Reply

Alvaro Cerezo June 24, 2019 at 8:40 pm

??

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big chungus January 16, 2019 at 11:30 am

alex franics manning sucks his mum

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Alvaro Cerezo June 24, 2019 at 8:38 pm

??

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Ash February 11, 2019 at 4:18 am

Interesting read! Very well written, thank you.

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Alvaro Cerezo June 24, 2019 at 8:38 pm

Thanks for reading!

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you're all gay December 5, 2019 at 1:16 am

fuck you

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Bill Nye The Science Guy August 28, 2019 at 8:57 am

All of you are literally insane for believing any of this. I am Bill Nye, THE SCIENCE GUY… and i am here to tell you that i have drank sea water for WEEKS almost every time ive been lost at sea, and have been HYDRATED AS CAN BE, infact, i bottled it all up in a parachute that i had stored my anus and dragged it to my island because i didnt want fresh water, eww. Now being rescued by 44 agents from CSI miami, the girls from teen mom, and walker texas ranger himself dressed as bruce lee in a python movie, ive been at home making sure to put loads of salt in all of my water. Im like shamoo in this bit! I BLOW SEAWATER OUT MY ARSE AND I LIVE IT. Freshwater is my kryptonite, EWW JUST EWW. Bobby booshae lovin criminals. If you are lost at sea, make sure you rub those coconuts all over your nips and balls for foreplay then insert into the arse for real fun. Holla at me DAWG, find me at myrtle beach or panama city slayin saltwater COCKtails with all my real onees u feel me BITCH. Yassssssss mmmmmmmmm SALT COCK!

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you're all gay December 5, 2019 at 1:15 am

you’re fucking retarded and alvaro is gay

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