It's fun for adults too. To give you an idea of the water area. DH and DD swam out to it. They went down the slides side by side. DD (4) picked the open slide and DH went down the closed tube. His was so fast, when he hit the water, his sunglasses broke at the nosepiece and it took him a few seconds to get oriented and realize he couldn't touch and therefore neither could my 4 y/o (6'1" vs 4'0"). Thankfully she's an great swimmer and had come up fending for herself.They have complimentary life vests before you swim out to that area and when we went they had a lifeguard there to pretty much encourage all kids to wear them.
They had a blast on the beach and my older niece had fund snorkeling and kayaking too. I've only seen great things about it. I wasn't feeling well, so I stayed on the ship and vegged alone.