Papa Hog's is one of the better-known scuba operators in Cozumel. They run small groups (6-8) in their boats and offer snuba and snorkeling, as well as scuba trips and the 'discover scuba' program. Their prices are significantly lower than what is offered by the cruise lines *and* the groups are much, much smaller. They are located near the Punta Maya port, just outside of downtown Cozumel.
Our group undertook a snuba trip. This requires no previous diving experience, though I myself am certified. Our dive instructor/leader, Julie, was very helpful. Snuba is much like scuba in that you breath through a regulator and wear weight belts to help you sink. The difference is that your airtank floats on the surface of the water in a raft and two people share one tank using air hoses. Also, you are limited to 20 feet depth, thus you needn't worry about equalizing on the ascent (only the descent).
We swam out from the shore to our reef, slowly descending to around 20 feet. The reef is protected by buoys, so there is little boat traffic. We didn't see any other divers, snorkelers or snuba'ers until the last few minutes. We got to spend the 25 minutes underwater pretty much alone. Visibility was only marginal, due to winds.
The reef itself is nice, but has suffered damage. There were many varieties of hard corals and a few anemones. Fish life was varied, and included some Sergeant Majors, Gray Angelfish, a Moray Eel, and some Butterflyfish. The sea life in this area cannot compete with the Great Barrier Reef, but is certainly worth a look.
After our journey, we returned to the shore and took our equipment off. The day we dove, it was extremely choppy and this made getting in and out of the water more difficult than usual. Our dive guide and the entire team at Papa Hog's were very helpful in that capacity. Should I return to Cozumel, I would not hesitate to use their services for a diving tour.