Isle Royale National Park

An island archipelago in Lake Superior accessible only by ferry or seaplane. Isle Royale is the least-visited national park in the lower 48, and the only one that closes entirely for winter — it attracts 86% fewer visitors than Congaree National Park. The wolf-moose study here is the longest continuous predator-prey research in history — running since 1958. You can backpack the 42-mile Greenstone Ridge Trail end-to-end in four days without seeing another person.