The Coppola family also operates the Turtle Inn, which is on the mainland as well, but on the beach (near Placencia) and offers scuba. I haven't stayed at either, so can offer no opinion about the resorts. I have visited both Ambergris Caye and Placencia, however, and - if you'd like to combine your diving with a lot of topside adventures - then staying at a mainland southern beach resort might be a good option. (We thought the diving from Placencia was very good, and also enjoyed our visits to Mayan ruins, the Monkey River tour, hiking and jungle walks, etc). Cheers!