Abstract: A trailer for transporting a pontoon boat behind a tow vehicle. The trailer is provided with wheel assemblies that can be moved longitudinally on the trailer's frame to adjust the load on the tongue of the trailer and is provided with rails that can be adjusted in width for receiving the pontoons of boats with different pontoon spacing. The trailer frame can be pneumatically raised and lowered on pivoting wheel brackets and each set of pontoon rails is provided with several pneumatically retractable rollers that can be raised and retracted relative to their associated rails to assist in loading and unloading a pontoon boat from the trailer. When the boat is not being transported, the rails and associated rollers can be removed from the trailer so that the trailer can function as a flatbed trailer.