We did this in 6-02. We really enjoyed it.
The boat ride is about 45 min. There are non-motorized water craft for rent. There is a shallow inlet that is great to enjoy the water especially if you have little ones. DS was 11 and we both enjoyed this area.
There are other areas to swim in that are on the "outside" of the island, but we didn't get there.
We did enjoy snorkeling here. We had our own equipment, but we had to rent vests at $5 a piece. It was pretty rocky getting into the area. I wore my water shoes out and snorkeled without fins. I had no desire to walk over the rocks bare foot.
If you have little ones, the snorkel area is also great because again it is a shallow entrance and there are lots of little creatures to watch.
The lunch provided was ok. It was your typical BBQ. They did take pictures that you could buy on a cash basis ($10).
There were 2 trips back, one at 2 and the other at 4. We were more than ready by 2.
They also had hammocks, basketball, volleyball.
I don't know if much has changed since 2002, but we had a great time.