Thunder Hole

Thunder Hole is a sea-carved rock inlet on the rocky eastern shore of Mount Desert Island in Acadia National Park, Maine, just under two miles from Sand Beach. It lies on the Park Loop Road. When waves are forced into the narrow channel, the air escapes with a loud boom, and spray can rise more than 12 metres (40 feet).

Steps lead down from the parking area above; from the platform you look toward Sand Beach and the Otter Cliffs. The upper platform is wheelchair accessible, while 55 steps lead to the lower one. According to the National Park Service, the lower stairs and deck are often wet and slippery, and waves can wash over the rocks even in calm weather. Parts of the walkway close during storms.

For the best experience arrive one to two hours before high tide. To see the carved cliff walls up close, come at low tide. Lonely Planet advises early or late in the day, as it gets crowded on fine days. The free Island Explorer bus stops near the parking area. For entrance passes, check the park’s website in advance.