Minibus tour drivers are usually waiting for arriving ferry passengers at the ferry port. A four-hour guided tour that makes a nearly complete circle around the island costs between €12 and €15. Stops on the tour usually include a distillery, the Ste-Marie Hospital parking lot (best view on the island), a shop where people make manioc flour, and an abandoned slave plantation.
The buses will sometimes leave you on the beach in St-Louis for a few hours and pick you up in time to make the boat back to the mainland. Some of the tour guides don’t speak much standard French, let alone English, so be sure to converse a bit beforehand to make sure they can explain everything clearly.