you can not get around roatan by yourself, you must take a taxi or an excursion. Last yr we went to Roatan and rented a taxi for the day, I think that is how they do it there, not sure you can get a taxi there and then one back. anyway we had the driver show us the island, which is very poor in places but absolutely beautiful, then had him take us to the beach and I believe it was tabayana beach.
the taxis in roatan charge by the person not by the trip as they do in America. It cost us 50 dollars for 2 people for the whole day.