My roomate insists that he cannot float. I told him I thought it must be a matter of technique, that if he relaxed and did it right he would in fact float. He still insisted that under no circumstances could he float, saying that his body was unusually dense. Aware that he is in many ways unusually dense, I hesitate to believe anything he says. But I wanted to be sure, so give me what you got folks. Does any human body float in water?



Having higher body fat (if that what you mean by dense) would probably help a person float. And, of course relaxing & filling ones lungs with air helps.

The salt content of the ater also makes a big difference. It is much easier to float in the Dead Sea than in Lake Huron!

Just not in the Dead Sea.

Why? One bobs around on the top of the water there.

I assume, actually, what he meant by “dense” would be a higher percentage of muscle, rather than a higher percentage of fat. I suppose if he has the low body fat of a male Olympic marathon contestant, he may experience more difficulty floating in fresh water. Should be fine in salt water, though.

People with low buoancy do exist - some of us can’t float on our backs. (I was a lifeguard in my younger days, so technique was not the issue). The “dead man’s float” method, face down and simply dangling, works on everybody I’ve ever seen - including some gymnasts and ballet dancers, none of whom had much body fat. Why not drop by a swimming pool with him and try? If the issue is a head full of rocks, you’ll be minus one stupid roomie right away. Collect next month’s rent up front, though.

Right. I was trying to make a joke and ended up not even worded it correctly so it just sounded wrong. Please just ignore my posts in this thread. I’ll leave now.

Thank you seawitch. It makes sense that people with different % body fat (what he meant by ‘dense’) would have more or less difficulty with floating. Rocks in his head may very well be the problem: I asked him what would happen if I shot him dead and threw his body in the ocean - his corpse, according to him, would sink to the bottom.

My brother-in-law is an ex-gymnast. As such, he used to be rail- and whippet-thin, with lots of muscle. Being an ex-swimmer, I didn’t believe him when he said he didn’t float.

Microbug and I took him swimming one time, though, and it was true; the guy sank like a rock. Even with full lungs, straight to the bottom.

My mother has taught swimming since the 1940s. In that time she has had one student sink to the bottom. She was teaching at a Boy Scout camp and asked the scouts to jump into 6 to 8 foot deep water. One kid jumped in and sank to the bottom, staying there without moving until she fished him out.

It’s possible that he had a ridiculously low amount of body fat, but I really can’t explain why he didn’t float.

…But Lightnin’ can (sorry, didn’t see your post.)

If you go swimming with someone and they seem to sink to the bottom, does that really mean that they cannot float, or simply that they are imperceptably dropping (on back) or thrusting upward (on stomach)their butt? My previous argument: if that person were to die, wouldn’t his/her corpse float?

A corpse may or may not float at first - but after a few days, they tend to develop internal gasses that cause flotation. Thus the importance of the concrete overshoe.

I have never been able to float. I’ve had several people try to teach me, including my ex-wife, who passed the lifeguard test during high school (I have no idea what that test entailed, I just know she loved to swim, took the test, and passed.)

I even sank in the Great Salt Lake. When I was about 14, I was on a family outing to the lake, and was playing in the water with a couple of my siblings.

We all knew no one could sink in the GSL (high salt & mineral content gives the water a specific gravity somewhat above the human body and all that), so I decided to try it.

I got to where I had (almost) my entire body floating except for one hand. I was kind of on my back, but turned enough to one side so that I could keep one hand on the bottom.

I yelled to my mom and said something like “I’m almost floating” (I had never been able to float in a pool). She said something like “go ahead and pick your hand up, you can’t sink here even if you try” and so I did. Went straight to bottom. Man that salt water stings the old eyeballs!

At the time, I was about 5’ 9", and maybe 110 to 120 pounds. Defintely skinny, but not incredibly so.

But I’ve never been able to float.


The human body is roughly the same density as water… seems that when you breath out you start to sink, breath in and you’ll just float. A denser than normal person may sink, but it also has to do with how you hold your body. Anyone can simply STEP off the side of the deep (15’?)swimming pool and sink down to touch the bottom if they expell all their air and hold their bodies straight up and down. All it takes is a little leg or arm movement (treading water) and anyone should also be able to keep their entire heads right out of the water. Not too many peole just jump in the water and remain motionless, so your sinking/floating tendancy shouldn’t play too much of a role in the short term since you’ll be doing some sort of swimming or treading stroke. In short, you can cause yourself to sink if you want to… and I suspect that a person with a denser than normal head would purposely do it just to show the world how “special or cool” he is. Then again you could always strap a pair of rubber ducky water wings on him if you’re concerned.

Sorry folks,
I just don’t buy that a living person can’t float.

Background: I was USN Aircrew for 24 years. Every 3 or 4 years I was required to go through (and pass) water survival training. These in-the-water day long sessions involved donning full flight gear that weighed about 20-25 lbs dry. Naked, I weighed around 145lbs at 6’3" and had a measured body fat of about (or less than) 10%.

They throw you in the pool with the helmet, boots, gloves, flight suit, survival gear, radios, etc. No survival gear is inflated and you’re use a technique called “drown-proofing” for about 10-15 minutes. First time I ever went through it I knew I was a dead man; but the technique can work for anyone. Plenty of time to take you boots off, tie them together and hang’ em around your neck, plenty of time to take out your radio, plenty of time to take out your strobe light, etc., etc.

In proving his point that drown-proofing works, the instructor also (loosely) tied my ankles together and my wrists together behind my back threw me in the pool and had me “swim” like a porpoise to the other end and back.

Motivation helped in this case, but I don’t believe there’s anyone that couldn’t practice/learn the techinque. It’s just too simple to screw up.

Skinny sinks quicker than fat, but technique is an equalizer.

I couldn’t float when I was a kid, at least up until sometime in my 20’s. Floating on my back was completely out, if I had to do any kind of swimming test that involved doing that I simple tried to tread water without being too noticeable about it.

I got called on this one summer in Boy Scout camp, and the life guard wouldn’t believe I couldn’t float. He had me fill my lungs full of air and go limp. I gradually drifted to the bottom of the pool and stayed there until I needed to come up for air, and he left me alone after that.

Now some of the muscle I used to have has turned to fat, and I float. On my back is still out, but if I fill my lungs and just relax I float just fine.

What’s all this about the different positions? If your body has a density lower than water, you can float in any position. If your body has a density greater than water, you can’t float at all. You can’t change your volume (or mass, of course) by any significant amount just by turning over on your back or on your stomach. You can change your volume by inhaling or exhaling, and there’s probably some folks who can float or sink at will by breathing, but that’ll hold true regardless of whether you’re on your back or belly.

Body position is imporant not so much in the theoretical sense of “can this body simply bob at the surface?”, but is quite important in the realistic situation of “can this person float in a position that’ll prevent him from drowning?” (assuming we’re talking about living people and keeping them living through the experiment). As I mentioned in my first post, a (conscious)person doesn’t get tossed into the drink and remain completely motionless. You’ll need to breath… meaning you’ll need to be able to get your face out of the water. You might be able to get density to float you head down feet up like a fishing bobber, or face down, or any number of positions, but that won’t do you much good when it’s time to take a breath. No human will float on top of the surface like a peice of styrofoam; you’re usually mostly submerged… and only a couple positions will keep your face above the surface.

I can’t float in fresh water.

Or at least I can when my lungs are full - if I exhale, I will sink slowly until I gently come to rest on the bottom, even if completely relaxed, regardless of whether I start from floating on my back or ‘dead man’s float’ position.

FTR I’m a strong swimmer (weekly visits to the pool for a mile’s swim), but I’m not devoid of body fat (mmmm, chocolate)

I can float in the sea though.