I have heard of a few options, such as a "float strap"(example), the rubber strap that comes with 35mm disposable cameras(example), and a wrist mount(example).
I have heard of these, but have no experience with any of them. I will be snorkeling not scuba diving, and want two things: not to lose my equipment, and to be able to take pictures of fish. What will best help me accomplish this? If it matters the camera will be a GoPro 960 and shooting in burst or time-lapse mode.