 SR 3 leaves US 1 at The Triangle, an intersection at the south end of Ellsworth that has been the center of numerous traffic problems within that city .Continuing south through Trenton, the route crosses a causeway to Mount Desert Island and intersects with SR 102 and SR 198, which run along the island's western side.SR 3 turns east follows the eastern shore to the tourist town of Bar Harbor, then continues south through Acadia National Park to the village of Northeast Harbor.