There is a whole spectrum of human body types but they can pretty much be nailed down to 3 factors: Bone Fat and Muscle Of course skin plays a role and several other things play a role but those 3 I listed above are the primary factors. In fact, you can think of these as axes in 3D space. So you basically have a cubic spectrum. The way I personally think about it is that the X axis shown in red represents the muscle, the Y axis shown in green represents the fat, and the Z axis shown in blue represents the bone. The center of the cube, that would be like your general human physique. Rarely does someone have those equal proportions of fat, muscle, and bone and even if they do, they still tend towards underweight of overweight with those proportions. Here are the extreme ends: This would be almost 100% fat. Of course there has to be some muscle and bone for us to survive and move the way we do but still this would be very high up on the Y axis but very little on the X and Z axes. Ignoring the side effects of obesity, people with more fat are better swimmers than very skinny people because fat has a low density, lower than that of water, so these people would be very buoyant. Then there are the extremely bony people, very skinny. These are people with muscular dystrophy and/or anorexia. Neither one of them is good but anorexia is worse. If somebody like this was trying to swim, that person would probably fall down to the bottom because bone is very dense. High on the Z axis and low on the other 2 axes. Then there is the best of the 3 extremes in terms of health, extremely muscular. These would be the bodybuilders. Robin, one of my fictional characters, can easily carry a male black bear and would fall into this muscular category. I don't know the density of muscle relative to water, otherwise known as the specific gravity of muscle, but I do know that these people would be very powerful swimmers and would thus go a longer distance than fat and bony people in the same amount of time. Fat as I described earlier is very buoyant so they would go further than bony people would. Bony people would most likely inch through the water, struggling so hard but eventually end up sinking and would need rescued from drowning or near drowning. But yeah as I said there is a whole spectrum of body types. And you could even make a 2D spectrum of the types of fat accumulation and body fat %. But going back to the 3D spectrum, there are so many body types, if I wanted to diagram it, where would I start?