We stayed at the Blue Marlin on our recent trip to Belize. South Water Caye is about 45 minutes from Dangriga and is a small island that has three resorts on it. Even though the island is about a mile long by about 2 blocks wide the three resorts don't seem to get along very well. I think this is planned so that they can each have the guest of their resort be committed to the services (food, drinks, snorkeling, diving, etc.) of that resort.
We booked our trip online and paid plenty for the one week stay and airfare. What I didn't realize is all of the added cost that wasn't included. The flights included in our booking was into Belize City and didn't include the short (25 minute) flight from Belize City to Dangriga (an additional $163 per person round trip) and the 45 minute boat ride (an additional $135 per person round trip). The meals are also an additional fee ($2,145 per couple including snorkeling). Don't forget to add the 12.5% sales tax and 10% service fee to everything.
The staff was great. They where very friendly and did what they could within the obvious boundaries in place my management. The food was American fare and was average in quality. For the price charged you would think the food would be better but in general it was OK.
In short, if I knew all of the add-on fees that wheren't included initially I wouldn't book with them again, a $4k to $5k trip should be a lot better quality than Blue Marlin.