You'll need a standard GoPro tripod mount ($4), 1/8th inch bolt and nuts ($1), a pack of Sugru ($2, or the free DIY Oogoo), 1/8th rubber washer ($0.20), Coke bottle cap.

This trick uses a plastic soda bottle to make a simple, floating mount you won’t lose under water. The video above, from DIY Photography, is as simple as it gets.