Flood isn't something that will occur randomly, your government should had warn the citizen for upcoming big flood. If I live in a country where extreme floods is nothing new, I would wear secret stash bracelet. Change the keys with laminated paper which I wrote my seed phrase, so it can resist against water.

No one will know if my bracelet contain almost all of my wealth.


https://www.yankodesign.com/2013/04/16/wear-your-secret-stash/