Someone asked about utilizing your trousers for survival. Here is the Navy's water survival instructor manual
https://www.netc.navy.mil/nascweb/mo...ombined%29.pdf
Tie your pant legs off in a knot at the ends. Either use the overhead method to slam the trousers into the water to force and trap air into the legs or use the splash method w/ your hand to force water in. Once you get enough air place the trousers under your mid section. Pictures are worth a thousand words. The pdf via the link above chapter 6 has pics and other open water survival techniques