On the simple side, the Hotel Garrafon was $2 for entry to the snorkeling area which had beach chairs, a small restaurant, a shark tank, and a nice though small area to snorkel. The reef is not lively, but there are lots of fish to see. They rent all the equipment you need as well. The menu was limited, but the food was good, the service friendly, and the beverages were cold... what more could you really want?

Here's their website.

Next door is Garrafon Park, which is a more of an activity park with snuba, a zip line, a larger snorkeling area, larger restaurant, a pool, kayaks, gift shop, etc. It is very nice, though busy and of course expensive. It was about $20 each if I remember for the all-inclusive, which did however include all food and beverages. Since we had biked from the north end of the island we were hungry and thirsty, so that was a good deal. It makes sense if you are going to make a day of it as far as food and drink. The food was good and the service friendly. We stayed for several hours and had a good time, beautiful views, and a very nice facility.

There is also a beautiful walkway along the ocean that will take you to Punta Sur, the very south point of the island. Plus a pair of resident parrots that seem to enjoy all the attention they get.

Here's their website.

Depending on budget, kids (there's more to do at the Park), and personal preference, either would be a good choice for a good time.

If you're not into snorkeling, a trip to Punta Sur for the small ruins and the beautiful walkways is a good way to spend some time. Punta Sur is just past the entrance to Garrafon Park.