In the past three years, I changed my hairstyle from shoulder-length, to a buzz cut, to a long, layered style. As I was growing my hair out from the buzz-cut, I dove with almost every imaginable length of hair. The best was when my hair was boy-cut. The worst was when my hair reached a jaw-bone length bob (impossible to tie back, but too long to let free).
Controlling long hair when diving is important for two reasons. The first is that long hair floats in front of a diver's field of vision (and gets horribly tangled in the process). The second is that loose hair tends to slide around under the mask strap, which causes the mask to move during a dive. Here are some tricks to control long hair that I have learned after years of diving.