No lifeguard, no skills, can save a person when lost in deep waters. In such circumstances, you bank on three things:
2) drinkable water
3) location info, so that the rescue crew can get to you.
‘Ocean Rescue’ by Seol-Hee Sohn, Seung-Hyun Yoon and Cheol-Yeon Cho, is an ideal device for such a situation. It provides you with distilled water; it emits light by night and colorful smoke during day time (so that the rescue party can get to you at the earliest). No need to worry if you’re born lucky, but those not in favorable terms with luck – This can be a ray of hope, if not an ultimate solution.