The area is very sandy and has a large number of areas with shading (I remember tarps, etc.) You definitly do need to sunscreen heavily because even though they are in the shade, they are also in the sun a lot. They do have water available at all times for the kids (whether on the ship, or on CC). That's the only thing they'll give them, except at the official meal times when they go to the BBQ and can get the punch, tea, water, etc. that is available to everyone.
The entire area is enclosed. You will go in and out through a gate. They will take them over to the BBQ place if they are in the program during lunch. That is an open area, but they are in their own pavilion there. Overall, it's a pretty secure situation, but there would always be a way for a child to slip away. It wouldn't be easy, but it wouldn't be impossible.
My son absolutely loved the program at Scuttles. He didn't care about swimming on the beach, he just wanted to stay there all day. My daughter wanted to swim, so she only visited Scuttles just for a little bit while we went to the adult beach. Even though they don't take them to swim, they do a lot of water based activities where they either spray them with a hose, or have them splash around. It's definitely a swimsuit place.
Not sure how old your kids are, but my kids have always been lab age (between 8 and 12). At that age, they wouldn't want Mom and Dad to hang out while they play. I'm not even sure if Mom and Dad would be allowed to stay the whole time they are there. One time when we were picking up DS, they were having a sand sculpture contest, and he wanted to wait for the judging to be done. We hung out for about 15 minutes then, and felt pretty awkward. I don't think that you could just go over to the Monstro dig (for instance) on your own. That's scheduled as a group club/lab activity with different times for different ages.
You will have to choose what you're comfortable with (and what makes your kids happy), but my experience is that if your child doesn't like the set up, they will page you. It's not like you just drop them for the duration. I'd recommend that you at least try it out, assuming that your child has enjoyed the kids programs on the boat.
