Talus caves in the boulder jumble near Millinocket, deep enough and shaded enough that ice survives in them through the summer, sometimes into August. You climb down a ladder into the main one and the temperature drops thirty degrees in a few feet. The trail in runs through the Debsconeag Lakes Wilderness with Katahdin in the distance. Bring a headlamp and traction, because the floor is literally ice in July. PUBLIC trail (Nature Conservancy land), near Millinocket.
Maine
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