Thunder Hole

Granite inlet that roars when waves compress at high tide—wave spray reaches 40 feet. Visit before high tide.

Natural Attraction

Natural Attraction
Geological Formation0 ftmid-April - early December$35 park entryRestrooms availableNo permit neededGolden-hour pick

At high tide or during storms, Thunder Hole transforms into a roaring spectacle as waves compress into a narrow granite chasm and expel trapped air with thunderous force. The inlet was carved over millennia by wave and tidal erosion into the eastern granite shoreline of Mount Desert Island. Descend the stairs at low tide to examine the smoothed cliff walls and cavitation pits—evidence of sustained wave abrasion. Visit 1–2 hours before high tide for the best acoustic and visual experience.

Getting there & parking

How To Get There
Located on Park Loop Road (paved, eastern section) on the rocky eastern shoreline of Mount Desert Island. Park in the small lot with wheelchair-accessible reserved spaces. Alternatively, walk Ocean Path trail to reach it. Island Explorer shuttle (free, summer only) stops here.
Road Type
Paved (Park Loop Road)
Parking Availability
Small parking lot; fills by 8–10am during peak summer season (June–August); wheelchair-accessible reserved spaces available
Peak Fill Times
Parking lot fills by 8–10am during peak summer season
GPS Coordinates
44.3210037005,-68.1890475002

When to go

Best Time To Visit
Visit 1–2 hours before high tide with incoming swells. Wave height matters more than tidal height—storm surge and Atlantic swells increase the phenomenon's intensity.
Best Visit Times
Early morning (before 9am) or after 3pm during summer; shoulder season mornings for solitude
Sunrise Sunset Quality
Sunrise: strong eastward light on cliff faces and spray creates golden illumination; sunset: backlighting over Atlantic swells creates silhouette drama
Best Season
Summer (June–August) for reliable access and stable weather; shoulder seasons (May, September–October) for fewer crowds and larger Atlantic swells
Busiest Season
Summer (June–August), especially July–August when Island Explorer shuttle operates
Seasonal Access
Park Loop Road typically open mid-April through early December (weather dependent)
Road Opening Dates
Mid-April (typical); Park Loop Road typically opens mid-April
Weather Patterns
Atlantic coastal weather with frequent fog in early summer; afternoon thunderstorms July–August; larger swells September–October and winter storms increase wave height and phenomenon intensity

What you will experience

Attraction Type
Geological Formation
Main Features
Granite inlet with narrow channel; wave compression and air expulsion phenomenon; 40+ foot wave spray potential; carved granite cliff faces with striations and cavitation pits; tidal variation effects; accessible viewing stairs at lower cliff level.
What Youll See
Granite inlet with narrow channel; wave compression spray; smooth cliff faces scoured by wave abrasion; cavitation pits and striations; Atlantic swells and surge; tidal variation effects
Unique Characteristics
National Park Service passport stamp location; wave-carved granite inlet listed on National Register of Historic Places; houses historic 1934 WPA-era ranger station (now gift shop)
Photo Opportunities
Wave spray silhouetted against sky at high tide; sunrise light on cliff striations; wave impact spray with mist backlit; sunset over Atlantic swells
Best Viewpoints
Upper parking area for wide-angle wave spray observation; stairs midpoint for wave height perspective; lower cliff viewing for close-up erosion detail and texture
Geological Formation Type
Wave-carved granite inlet (coastal erosional feature)
Scientific Interest
Coastal wave erosion mechanics; granite abrasion patterns and cavitation evidence; tidal phenomenon with compressed air expulsion; subsonic wave energy conversion

Facilities, fees & access

Entry Fees
$35 per vehicle (7-day pass); $20 per person (7-day pass); $30 motorcycle (7-day pass); youth 15 and under free
Permits Required
0
Restrooms Available
1
Picnic Areas
0
Water Available
0
Interpretive Signs
1
Accessibility
Paved parking lot with wheelchair-accessible reserved spaces. Upper viewing area accessible via paved walkway. Optional stairs and accessible ramp with switchbacks for descent to lower cliff viewing area (reconstructed 1992–1993).
Accessibility Level
Drive-up view with optional stairs to lower cliffs
Nearby Services
Hulls Cove Visitor Center (southwest via Park Loop Road); food, lodging, and supplies in Bar Harbor town
Nearby Facilities
Thunder Hole Gift Shop (snacks, souvenirs, housed in historic 1934 ranger station); restrooms; accessible parking
Family Friendly Notes
Accessible for families with children, but requires supervision due to cliff edges and rogue wave risk. Railings and reconstructed walkways in place. Rule: never turn your back to the ocean, keep children at arm's length near water.

Safety

Safety Considerations
Rogue waves can wash over surrounding granite ledges without warning, even in calm weather—never turn your back to the ocean. Cliff edge exposure is significant; stay behind railings. Wave spray reaches 40+ feet and water is 40–50°F year-round. In storms, sections of walkway close. Supervise children carefully.

Nearby

Nearby Attractions
Ocean Path Trail, Otter Point (adjacent on Park Loop Road), Sand Beach, Jordan Pond
Connecting Trails
Ocean Path Trail
Trailheads Here
Ocean Path Trail

Planning advice

Insider Tips
  • Timing is everything: high tide with incoming swell = roaring phenomenon; low tide = quiet but reveals erosion patterns.
  • The granite cliff walls are smoothed and polished from abrasion—run your hand along them to feel the wave-worn surface.
  • Passé stamp collectors: this is an official NPS passport location.
  • Summer weekday mornings (before 9am) offer fewer crowds and reliable weather for photography.
Tips Advice
  • Listen for subsonic rumble as compressed air exits the chasm—it's wave energy converting to sound in real time.
  • At low tide, examine granite for smooth scours from wave abrasion and deeper pits where cavitation occurred.
  • Wave spray contains sand and fine debris—observe air-abrasion polishing patterns on exposed rock faces.
  • Bring a rain jacket if windy; spray is saltwater and cold.
  • Never put hands near surge channels or unrailed ledges. Water temperature stays 40–50°F year-round.

More details

Park Area
Eastern shore, Park Loop Road
Recent Updates
Accessible ramp with switchbacks reconstructed 1992–1993; walkway systems upgraded in 1960s; restrooms constructed in 1982; gift shop operates in historic 1934 WPA-era ranger station
Elevation Feet
0
Visitor Center Present
0
Guided Tours Available
0
Fishing Nearby
0
Swimming Allowed
0
Boating Allowed
0
Climbing Areas
0
Review Summary
Visitors consistently appreciate the unique acoustic and visual phenomenon; many understand the wave erosion mechanics after visiting. Disappointment occurs if tides or swells don't align, emphasizing the importance of timing. Most rate it a must-see on Acadia itineraries for the roaring effect and dramatic granite coastal landscape.

Location

Frequently asked questions

Is the roaring sound really that loud?

Yes. Compressed air exits the chasm with explosive force, creating subsonic rumble audible from the upper parking lot. During large swells, it's genuinely deafening. The sound is pure wave-driven physics.

Do I need special fitness or skills?

No. Upper viewing area is car-accessible with paved walkway. Optional stairs lead to lower cliff faces but aren't required. Railings and reconstructed walkways are maintained and safe.

What's the best time to visit?

Visit 1–2 hours before high tide with incoming swells or storm surge. At low tide, it's quiet but you can inspect erosion patterns and striations close-up on the cliff walls.

Is this safe for kids?

Yes, with supervision. Railings, stairs, and paved pathways are in place. Rule: never turn your back to the ocean, keep children at arm's length near ledges. Water temperature is 40–50°F year-round.

Can rogue waves wash over me?

Yes—rogue waves can wash over ledges without warning, even in calm weather. This is why railings and maintained walkways exist. The stairs and lower viewing area keep you at safe vantage points. Bring a rain jacket if windy.

Echo Lake

Dark waters in a granite basin. Swim the lifeguarded beach, paddle, or hike Beech Mountain from one lot.

Little Hunters Beach

Fist-sized cobblestones frame a secluded Atlantic beach. Glacier-rounded stones, slippery rocks, cold water.

Shatter Zone

Chocolate chip cookie rocks reveal an ancient volcano's caldera edge in granite.

Sources

Editorial review: YourNPGuide Editorial Team. Information is compiled from official sources, verified traveler reviews, and editorial research; no firsthand visit is implied unless explicitly documented. Learn how YourNPGuide works.

Last updated July 2026. Report an issue.