I have a rotting pair in the garage that got 2 years of use. I just find the Croc to be better all-around footwear for the price.Your criteria was boating/fishing. Not trudging through the bayou.
Even at that, questioning the durability of them makes you sound a lot like a guy who hasn't owned a pair and worn them hard.
If I wanted to be a true tool, I would get some high-end Sebagos