We did not take one of the excursions and had intended to go to El Cid (walking distance from the port) and pay $15 each to use their facilities for swimming and snorkeling. We wound up walking through the downtown area and further, finding a nice little boutique hotel that let us use their facilities as long as we spent $12 each. Had no problem walking around, felt safe, and it was nice to walk along the coastline. The snorkeling along the breakwall by the hotel was surprisingly good. We had our own snorkeling equipment.
We took an excursion here through Carnival, the Xunantunich ruins with lunch included. It's a four hour round trip but worth it, the guides were very informative and we learned a lot about Belize as well as the Mayan culture. The ruins themselves were impressive and the lunch was local (rice and beans with chicken) I would have liked to have done Lamanai because you travel partway by boat but that was not available through Carnival and I left the online booking too late. Carnival subcontracted to Chukka (time to play!) which I would recommend.
We decided to go off resort in Roatan so that we could see Honduras instead of just another resort. Carnival offers a shuttle for $20pp that goes to a public beach about 20 minutes away. It's a public beach, so keep your expectations low. Some of our fellow travelers were disappointed, but again .. it's a public beach so no fancy white sand or pretty cabanas. What you get is some pretty decent snorkeling, local food, and cheap beer. We had lunch at Cindy's place, but if I'd seen it sooner we would have gone to the Cannibal Cafe. There is a restaurant on the beach that will let you use their shower in exchange for buying their beer. We also spent some time on resort, which is gorgeous. Don't bother with the chairlift unless you have some walking problems. The beach is a 5 minute walk from the pier.
This was fantastic. We negotiated a price with several operators after getting to port and it was worth the trouble. Stingray city is amazing and Native Ways took us to two different places to snorkel afterwards. Great deal and the boat operators were great. Even if you don't like snorkeling, you can do just Stingray City which is just over waist deep. They have equipment, but we had our own. And they have life jackets if you are nervous.