If this is how Labor Day is beginning...

[amphrite]

Honestly, my source is experience, and I don't think I related it quite accurately. I teach many many many children and adults every day, and I see it all the time. You ask my coworkers, and the lifeguard who have done this for 30 years and they all say the same thing. Of course, there are always exceptions. Now alot of it is Muscle. That is what makes you sink, especially when it is in your legs. So if you are a runner or a hockey player for example, you sink straight to the bottom upright. It is actually really funny to see. You need to take into account many factors, but bone density is one of them.


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clicky

[Chromatix]

This is actually true. Fat floats on water, but muscle is denser than that - a lot of people, when they start exercising properly, get thinner and a lot fitter but stay roughly the same weight, because the fat is being replaced by muscle. So I can completely believe that a very lean and muscular person could fail to float.

Which may itself explain why I tend to float quite low in the water. I'm a fairly good swimmer (at least, I was the last time I tried, which was quite some time ago), but I have to make at least some effort to keep my chin out of the water.