I can swim - Sort of

I remember as a child, I took swimming lessons at the YMCA. I remember doing well. Then, for many years, I did not have the opportunity to swim. When I did get back into the water, I was unable to swim. I was able to doggy-paddle slightly and swim underwater shortly. I accepted my fate as a non-swimmer.

In college, a couple of friends and I decided to take swimming lessons. It was a sixteen-week course. I was able to do most things, except float (on your back. I was able to float face-down, which doesn't help) and tread. I would tread for a few seconds and then sink to the bottom. When trying to float on my back, I will be relaxed as can be, then slowly water will cover my face and I continue to sink. When kicking as hard as I could, the lower half of my body (butt and feet) would slowly start to sink and proceed to pull me under. I baffled my instructor, who could not understand what was going on. She told me that it was like I was made of bricks. Honestly, that's what it feels like.

I am not scared of the water. I love to be in the water. I will even go to the deep end, as long as I have a flotation device or am near the edge. Once, when snorkeling in the Caribbean, I asked the rental guy for a life vest and he gave me this weird look and asked me why I needed one to snorkel. I think it is much easier to snorkel with a life vest on because you can just float around and relax without worrying about sinking.

A friend told me that people with higher bone density have difficulty swimming. http://en.allexperts.com/q/Swimming-Diving-1564/swim-float-2.htm
This link http://answers.yahoo.com/question/index?qid=20090814115534AAljg1Q says that people with more fat can float. I have a lot of fat on my body, but cannot float so there goes that hypothesis. If you think about it, all those Olympic swimmers hardly have any fat on them. Does this mean that they can't float either?

Last week, I bought swim fins, for boogie boarding. I wanted to practice using the fins in a pool before going out into the ocean. Believe it or not, I was able to swim and tread water. I then took off my fins and tried to repeat this feat, only to sink again.

I have very small feet for an adult: Women Size 5. I wonder if this has anything to do with my inability to swim. Do the fins make my feet longer and thus allow me to stay afloat? I don't understand.

At least I know I am able to swim in one form or another.