Yes the boats are uncovered so a hat and sunscreen are highly recommended. I also highly recommend those waterbottles that have a sprayer and little fan on them for comfort. (I had one once that is a pressurized insulated water bottle with a mister on it, I was VERY popular as the water was ice-water <G>) The boat trip is 1 1/2 hrs so go to the bathroom before you get on. A restroom is available at Altun Ha. The tour of Altun Ha is about 3 hrs and the return home is about 45 minutes in a nice air conditioned bus. Altun Ha is NOTwheelchair accessable it he requires one. Not many tours are really Wheelchair friendly in this country. The City Tour is pretty lame IMHO. Maybe the Powerboat Thriller? At least you rent a cart to explore the beach islands you visit but then again, if wheelchair bound it isn't going to work.