 In addition to nearly half of Mount Desert Island, the park designation also preserves a portion of the Schoodic Peninsula on the mainland, as well as the majority of Isle au Haut and Baker Island, all of Bar Island, three of the four Porcupine Islands (Sheep, Bald and Long), the Thrumcap (an islet), part of Bear Island, and Thompson Island in Mount Desert Narrows, as well as several other islands and islets.Bar Island, which can be visited on foot over a sandbar around low tide, and the Porcupine Islands are in Frenchman Bay by Bar Harbor.About of carriage roads were designed and financed by John D. Rockefeller Jr. on Mount Desert Island, of which continue to be maintained inside the park.