I bought these to wear at the beaches of Long Island.  On the south shore, where the beaches are fine sand, they work great and I love them.

On the north shore, the beaches are more fine rocks than sand.  The soft rubbery material of which the shoes are constructed will fill up with stones that get stuck in them.  They almost act like a stone sieve, with every hole filled with an appropriate sized rock jammed in the webbing.

On the fine sand, or on mucky lakes, these are great.  For stony beaches - not so much.