[power78]

> Furthermore, not everyone is positively buoyant. The less fat one has, especially if not wearing diving suit, the more likely staying afloat/level to become harder.

I'm not sure if it is just me, but I could not understand this at all. Do you mind rephrasing it? Which type of person has a harder time stating afloat?

[serkandurusoy]

Fat can naturally float on water due to its density being less than that of water.

The more fat one has, the less overall average density becomes, making it harder to sink. I have a close friend who is very overwheight and she can practically sit upright floating. I must admit I'd usually envy her when I struggled staying afloat while she enjoye a cool refreshment like it were her couch :)

So in short, less fat, more muscle mass, more bone mass harder to stay afloat.

Also the diving suite (which is made from a foam-like material) and some of the hallow diving gear make it harder to sink, hence the need for weights.

[IncRnd]

Fat has a specific gravity < 1.0, floating in water.

Bone + Muscle have specific gravities > 1.0.

Generally, the more fat on a person, the greater that person's buoyancy.

[whiddershins]

Higher body fat makes you float more easily. I think.

[mrkstu]

Muscle is denser than fat per volume.