Crash! Boom! Splash! Thunder Hole is one of the most unique (and popular) features in Maine’s Acadia National Park.
It’s a rocky inlet along the coast where waves constantly crash against the rocks, creating a thunder-like roar and dramatic splash of water into the air. Seeing it in person is a really cool experience.
Thunder Hole was one of the highlights on my own visits to Acadia, which took place as part of a road trip from Boston to Acadia.
Wanna see this awesome formation for yourself? Read on for all the details about a Thunder Hole Acadia visit, including how to get there, the best time to visit, how to see it safely, and much more.
Thunder Hole Acadia: Basic Info, Directions, Fees
Let’s go over all the most commonly-asked questions about the history and geology of Thunder Hole, and how to get there.
What is Thunder Hole?
As noted, Thunder Hole is a carved inlet that has become a popular tourist attraction because of its loud noises and eye-catching wave splashes.
Or, as Google succinctly describes it, it’s a “rock crevice with pounding wave action.”
The waves and thunder vary in intensity, so some days (or times of day) are more dramatic than others. But no matter when you come, you can usually experience the power of Thunder Hole to some degree.
Where is Thunder Hole?
You can find this natural rock crevasse along the Atlantic coast of Acadia National Park.
Thunder Hole, like almost the entire national park, is located on Mount Desert Island, an isle off the coast of mainland Maine. There’s a short bridge allowing vehicle traffic to reach the island.
Where exactly in Acadia National Park is Thunder Hole located?
Thunder Hole sits just off Park Loop Road, south of Sand Beach and north of Monument Cove and Otter Cliff. This part of Acadia has more interesting spots to visit than any section of the park.
How do you get to Thunder Hole Acadia?
Just follow the map above to the parking lot, which sits right across the street from Thunder Hole. Park Loop Road is a one-way road.
The parking lot has a gift shop, which was once the original ranger station for the park. It’s open 9 am to 5 pm from early May to mid-October. They sell drinks and snacks, but nothing refrigerated, since they do not have electricity.
If you arrive during a busy summer day, it’s possible the parking lot may be full, in which case you’d have to return later, or park at a nearby lot or pullout and walk over.
You can also get here using Acadia’s convenient shuttle system. Routes 3 and 4 of the Island Explorer bus make stops at Thunder Hole.
The buses run every 30 minutes, which is a perfect amount of time to visit this attraction.
Questions About the Geology of Thunder Hole
How deep is Thunder Hole?
The cavern itself is less than 20 feet deep. It’s hard to give an exact height, as that depends what the water level is at the time. Even though it’s not massively deep, it’s enough to create those thunderous reverberations.
What causes the loud noise?
As the previous wave retreats, air moves into the cave. The thunder-like sound is created when the next wave rushes over the air trapped in the chasm and forces it back out.
When is the thunder sound the loudest?
You’ll hear small booms no matter when you visit. But you can hear the most dramatic noises about 1-2 hours before high tide. Particularly loud thunder noises are also common after storms.
How big are the waves here?
It really depends when you come. Normally, you’ll see the occasional wave splashing a few feet above the rocks.
However, once in a while, especially after storms, waves have been known to approach 40 feet in height.
What is known about the history of Thunder Hole?
Thunder Hole was formed thousands of years ago by erosion due to the waves repeatedly battering the rocks.
It was mentioned in print as early as 1867, when a book referred to it as Thunder Hole or Thunder Cave, and described the site thusly: “The wave is thrown against the overhanging rock with a blow that makes the whole cliff shake and the air tremble as with the crash of thunder.”
A local group created hiking trails to the site in the early 1900s, and Park Loop Road was built in 1930.
The ranger station (now the gift shop) was built near Thunder Hole in 1934. Walkways were upgraded in the ‘60s, and then again in the ‘90s.
The Thunder Hole area is on the National Register of Historic Places.
Logistics of Visiting: Cost, Best Times, High Tide, Safety
Are there fees to visit Thunder Hole?
Yes, it’s $35 per vehicle (ouch!) to enter Acadia National Park. Unfortunately, that’s one of the more expensive entry fees of any U.S. national park.
Once you’re inside Acadia, there are no additional fees to visit Thunder Hole. Parking is free.
When is the best time to go to Thunder Hole?
For the best weather, the best time to visit is during the summer months, June through August. Temperatures are comfortable and the skies are typically sunny.
That said, many people do visit Thunder Hole during the winter, and the photographs can be spectacular, with the waves crashing while the rocks are covered in snow and ice.
Autumn is also a good time to visit since temperatures are still tolerable and the leaves are changing colors. Be prepared for strong, chilly winds along the coast.
As far as time of day, that depends on the tides. Arrive 1-2 hours before high tide for the biggest waves and thunder crashes.
When is high tide at Acadia National Park?
Use these charts showing the tides for the nearby town of Bar Harbor. Most days, there’s a high tide in the morning, and another in the evening.
Are there bathrooms at Thunder Hole?
Not at the site itself, but bathrooms are available in the parking lot across the street.
How long does it take to see Thunder Hole?
You could stay at Thunder Hole anywhere from 10 to 60 minutes, depending how much time you have.
Ten minutes is really all you need at Thunder Hole to see several wave crashes and get a good sense for the power of the waves and the beauty of the natural features.
The average person probably spends more like 15-20 minutes here, to go down all the staircases, walk around on the rocks, and take lots of pictures.
If you want to linger and have a more thorough Thunder Hole experience, bring lunch and sit on the rocks. I spent about 45 minutes here observing the site, doing some people watching, and enjoying lunch.
I don’t see much point in spending longer than an hour here, unless you’re a committed photographer looking for that absolutely perfect shot of the waves shooting into the air, and you’re willing to stay all day to get it.
How do you view Thunder Hole?
There are staircases leading down closer to the water that allow visitors to see the waves from a somewhat close distance. Or just take a seat somewhere on the nearby granite boulders.
Is it safe to get close to Thunder Hole?
Yes, but with some asterisks. The staircases have fences and/or railings to keep guests reasonably safe from any large waves.
Sometimes, like when I last visited, rangers may close off some of the stairs if especially large waves are predicted.
But there is still small potential for accidents. The rocks can get slippery, and it’s possible for rogue waves to appear out of nowhere and splash much higher than people are expecting.
In one such case, a woman was swept off the rocks not far from Thunder Hole and carried out into the ocean, where she was finally rescued 30 minutes later.
What precautions should I take when visiting Thunder Hole?
Just be careful about going too close to the edge of the rocks. And perhaps bring a wind or rain jacket for protection from the coastal winds and strong splashes.
Otherwise, if you stick to the marked paths and staircases, you should be fine.
Can I swim or wade in Thunder Hole?
There is nowhere to get into the water right at Thunder Hole itself, and you wouldn’t want to, with the rocks and waves in the area.
However, just to the north of Thunder Hole is Sand Beach, the only sandy beach in Acadia. Lots of visitors, including families with children, go swimming there, as the waters are calmer.
Can I bring my pet to Thunder Hole?
While most national parks do not allow dogs, Acadia NP is an exception. Dogs are permitted in the park if they are kept on a leash shorter than six feet.
The park website has a page detailing which sections of the park allow and restrict dogs. Thunder Hole is not specifically mentioned, meaning that the default park rule applies (dogs allowed on short leashes.)
Is Thunder Hole accessible for people with disabilities?
Yes. The path from the parking lot to the viewing area, and the upper part of the viewing area itself, are wheelchair-accessible. So are the parking lot and bathrooms.
Guests in wheelchairs will not be able to go down the staircases to get the most up-close view of the ravine, but they can still have a good viewing experience from the upper viewing section.
Can I bring food and drink to Thunder Hole?
Sure, it’s an outdoor area in a national park, so you can bring anything you’d normally bring on a hike or lunch break. The rocky outcrops are a good place to rest and enjoy lunch or a snack.
More Acadia FAQs
What hiking trail goes to Thunder Hole?
Most people drive straight to Thunder Hole. But if you want to hike there, the Ocean Path is the trail to use. It hikes the shore along this section of the island.
The walk along Ocean Path from Sand Beach to Thunder Hole is 1.7 miles each way, with only 196 feet of elevation gain. You could make the walk in 40 minutes (each way.)
Ocean Trail continues south down to Boulder Beach, Otter Cliffs, and Otter Point, so you could conceivably hike up to Thunder Hole from any of those spots as well, though the trek would be longer.
What else is there to see near Thunder Hole in Acadia NP?
Acadia has so many awesome points of interest. A few that should be on any Acadia NP itinerary:
Sand Beach. As previously mentioned, Sand Beach is a great spot for swimming and hanging out with friends or family along the shore. It’s one of the few sandy beaches in a national park. Wear your bathing suit and bring sunscreen!
Otter Cliff and Otter Point. Otter Cliff is a 110-foot-tall granite cliff on the coast, south of Thunder Hole. This section of the park has several impressive cliffs, finishing at Otter Point on the southern end of this peninsula.
Cadillac Mountain. Cadillac is the tallest mountain on the eastern seaboard, standing 1530 feet high. Drive there for awesome views of the park and the ocean.
For much of the year, Cadillac Mountain is the first place to see the sunrise in the U.S. on any given day! Because it’s so popular, vehicle reservations are required most of the year.
Gorham Mountain Loop Trail. One of the best day hikes in Acadia is Gorham Mountain, a 3-mile loop trail with 580 feet of elevation gain. For the best photographs, go in the afternoon, when the sun will be shining from the west and perfectly illuminating all your shots of the coast.
Hulls Cove Visitor Center. The main visitor center on Mount Desert Island, Hulls Cove is the place to get your park souvenirs and park maps, refill water bottles, use the restroom, and ask questions of the rangers.
Wild Gardens of Acadia. Founded in 1961, the Wild Gardens feature many of the plants from the various sections of Acadia National Park, all gathered in one place for easy viewing.
What is there to do in Bar Harbor, Maine?
When you visit Acadia, stopping in the touristy town of Bar Harbor is a must. Visit the gift shops, seafood restaurants, ice cream shops, art galleries and other fun places of interest.
Just park and walk down Main Street to take in all the excitement. Bar Harbor is a bustling community that always sees a ton of visitors.
Do you have any other tips or questions about visiting Thunder Hole Acadia?