Thunder Hole is an Acadia National Park classic. The narrow crevice on the coast catches incoming waves and sends them rocketing as high as 40 feet into the air. Best of all, visitors can follow a well-maintained path right down to the ocean’s edge in a fenced off platform.
Thunder hole is located on the eastern shore of the park, with a large parking area just off the Park Loop Road. To reach the iconic inlet, simply walk across the Park Loop Road and down the paved steps. It can also be reached from the Ocean Path. As one of the park's most popular attractions, it can be quite crowded. Fortunately, the open coastline just to the north offers great views of the exploding waves with less confinement.
Thunder Hole gets its name from the ominous booming that sounds with incoming waves. A small cavern just below the surface catches pockets of air as incoming waves suck water out to see. When they crash against the shore, the air bubble in the cavern explodes and echoes, creating a sound like thunder. It takes specific conditions to make the usual gurgling sound into the iconic peal of thunder; swells between three to six feet two hours before high tide are most likely to demonstrate the true power of Thunder Hole.
During heavy storms, massive waves can pound the relatively unprotected point of Thunder Hole. It's a great destination when the swells get big, but it becomes necessary to use extreme caution and stay far from shore. Rogue waves can reach much further than expected, sweeping those that get too close out to sea.