The beach that you can see when the ship is docked in St. Maarten has one and it is not an excursion. That is the beach we go to, we take the water ferry to downtown and walk to the beach, which is right next to where you get off of the ferry.
Our daughter the trampoline, $5 for as long as she wanted. She discovered it was harder than it looks. It swivels around with the waves. If you ask her she loved it but she didn't last long on it. It sure looked fun.
This is a beach where they rent wave runners also. The chairs are for rent and they belong to different businesses on the beach. Picture in your mind hotels and the grouping between the hotel width to the beach is their area of rental lounge chairs with umbrellas. Instead of hotels it is bars and some also serve food.
One caution, this beach has about a 2' drop not to far into the water. It slopes fast so watch little ones. Have fun. Kathy