on the beach

[dido4]

They are playing "on" the beach.
1. Can we use "at" the beach or "in" the beach?
2. What are the differences between at the beach and on the beach?
3. Is in the beach right?
thank you

[Tdol]

I'd use 'on the beach' for the actual area of sand and 'at the beach' fpr a wider area including restaurants, bars, etc. I wouldn't use 'in the beach'.