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Key Info

Park Loop Road

Price & Hours

24/7 daily


Natural Wonders, Free, Sightseeing Type
Less than 1 hour Time to Spend


  • 5.0Value
  • 3.0Facilities
  • 4.0Atmosphere

A raucous natural phenomenon, this semi-submerged cave booms an hour or two before high tide. Waves fill the cave in such a way that the slapping is as loud as a thunderstorm – hence the name – and water can spray as far as 40 feet, so wear a poncho if you want to stay dry.

To catch the big boom, there's an element of luck, as well as timing. Recent travelers said the best time to visit is when the tides are changing. Visitors also warned that it can be difficult for those with mobility issues to enjoy since the rocks can be uneven. However, those who can't make the descent can still see and hear the waves. If you venture outside of the viewing platform (which includes a railing and level steps), walk carefully; the rocks will likely be wet and slippery. When you're not admiring the spectacular show, take a moment to take in the views: you'll spot Schoodic Peninsula in the distance, Sand Beach to left and Otter Cliff to the east.

Thunder Hole is on Park Loop Road, just south of Sand Beach. This is one of the park's more famous attractions, and it can get crowded, especially in the summer. If you don't want to drive, you can hop on the Island Explorer shuttle (take Route No. 3), or you can hike. Starting at the Sand Beach parking, there's a nearly 2-mile-long trail called Ocean Path that hugs the coastline, bringing you south toward Thunder Hole and Otter Cliff.

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More Best Things To Do in Acadia National Park

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Time to Spend
#1 Cadillac Mountain

Standing about 1,530 feet in height, Cadillac Mountain wins a lot of superlatives. Not only is it the tallest mountain in the park, but it's the tallest mountain on the North Atlantic seaboard. Whether you hike up the Cadillac Summit Loop Trail or drive up the 3 1/2-mile narrow access road, go early. As the only attraction in the park that can be reached by car, Cadillac tends to draw crowds. If you do arrive by car, you should drive slowly, especially as the roadside cliffs get steep. Along the road, you'll find several small observation areas: take advantage of those before you reach the top, where the crowds and tour buses congregate.

For the ultimate vistas, set your alarm clock and try to catch a sunrise here. Cadillac Mountain is the first point of the United States to greet the rising sun's rays from early October to early March, and visitors assure it is a spectacular sight to see. While recent travelers said a trip to Acadia isn't complete without a stop at Cadillac Mountain, they also cautioned the area gets crowded, even in the early morning hours (some reported arriving two hours before sunrise). If you're visiting during the winter months, you'll have to hike the Cadillac Summit Loop Trail; the park closes down the access road for the winter season. Pack blankets and hold on to your hats, too, as it gets chillier as you ascend.

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