My experience of 40 years ago.
At the time I was still practicing free diving.
A free diver can stay in salt water several hours, compared with the 30-40 minutes of the single dive per day, deep and with short deco, which was typical for a scuba diver of the time.
So the exposure was much longer.
The osmotic effect of staying submerged in salt water for several hours was quite evident and confirmed by dozen fellow freedivers of my club.
Salt does not pass the skin barrier, but water instead does.
So you loose a lot of water through your skin and become easily dehidratated.
Usually free divers do not carry fresh water with them.
We learned the hard way how this is unhealthy. So we started carrying a bottle of drinkable water with us.
It is an impedment, but it avoids to become too much dehidratated.
Now, back to scuba diving.
In many parts of the world, and thanks to smaller depth, Nitrox, diving computers and much smaller tanks, nowadays also a scuba diver can spend 4 or 5 hours each day in salt water, experiencing the same problems.
So it is very important to drink a lot before and after each dive.
And, in my opinion, one needs to drink just water, as this is what is lost and must be reintegrated.
Instead when you loose water in other sports, for example running, you are sweating a lot.
This does not only expels water, but also salts. Hence a runner should not drink just water, special "sport drinks" have been developed for reintegrating the lost minerals.
If a scuba diver drinks such "salty" sport drinks instead of plain water, this is the mechanism causing to become "too salty".
Now, I am not a MD. So please can some of the people here with a proper medical education confirm that for a diver it is important to drink a lot of plain water, and instead it is better to avoid these "salty" sport drinks?
