Bathroom sandals for BIG feet.

I am looking for bathroom shoes in size 340, preferably online.

Bathroom sandals are usually built with plenty of holes making it breathable and such so it doesn't retain water and gross stuff. Sadly, I cannot find any close in my size. I've tried using Underarmor brand sandals for a couple years but they do not have that breathability, and I am constantly having to pry gross nasty gunk off of them. I live in Goyang and any help in helping me find these shoes would be a lifesaver.