The Sanuk Fraid Not sandal has a suede footbed so I wouldn't recommend trudging through the water in these. They are designed to be casual wear and not for technical purposes. That being said, wearing them to the beach should be fine and putting wet feet in should not do much harm.

The suede will prob be a little slippery, and because its not a shoe designed specifically for water it will most likely take a while to dry out.