At the Thunder Hole overlook, a wayside exhibit entitled "Icy Depths" features an informational panel angled atop the low stone wall.
Access Acadia: Inclusive Descriptions of Park Destinations
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Itineraries across USA
Acadia
Arches National Park
Badlands
Big Bend
Biscayne
Black Canyon Of The Gunnison
Bryce Canyon
Canyonlands
Capitol Reef
Carlsbad Caverns
Channel Islands
Congaree
Crater Lake
Cuyahoga Valley
Death Valley
Dry Tortugas
Everglades
Gateway Arch
Glacier
Grand Canyon
Grand Teton
Great Basin
Great Smoky Mountains
Guadalupe Mountains
Haleakalā
Hawaiʻi Volcanoes
Hot Springs
Indiana Dunes
Isle Royale
Joshua Tree
Kenai Fjords
Kobuk Valley
Lassen Volcanic
Mammoth Cave
Mesa Verde
Mount Rainier
North Cascades
Olympic
Petrified Forest
Pinnacles
Rocky Mountain
Saguaro
Shenandoah
Theodore Roosevelt
Virgin Islands
Voyageurs
White Sands
Wind Cave
Yellowstone
Yosemite
Zion