Never been to the beach, what do I need?

My husband and I are taking our 3 year old to the beach. I’ve never been, and my husband hasn’t been since he was 4. What things, other than sunscreen, do we need to bring with us?

And does anyone have a recommendation for where to buy swimsuits for giant boobs? I need some support, and there is no way anything on the rack at target is going to fit.