State Route 233 is part of Maine's system of numbered state highways, located on Mount Desert Island on the southern central coast. It is a short east-west highway, running 5.85 miles (9.41 km) and connecting with State Route 3 at both ends. SR 233 provides a direct connection between Mount Desert and Bar Harbor, which would otherwise require a lengthy drive on SR 3, which loops the entire perimeter of the eastern half of the island.
SR 233 begins in the west at SR 3 (also overlapped with SR 198) less than a mile east of SR 3's "eastern" terminus (at which point it is heading nearly due west) at SR 102. The windy highway cuts directly across the center of the island to Bar Harbor, where it rejoins SR 3 in the town center. There are no major junctions between SR 233's endpoints.