Where Are The Best Beaches For Small Children?

Hello - I have two small children in the toddler years.

I'm looking for a good beach destination with little surf, lots of sand, and as shallow an entry to the water as possible.

I saw that there is a beach in central america where it is only knee deep 20-30 yards out. I'm wondering if there are other beaches like this in the Caribbean or Mexico?

Where are the best beaches for small children?