Beneath the sandstone-capped ridges of Mammoth Cave National Park lies the most extensive known cave system on Earth, with over 350 miles of passageway mapped and surveyed. And yet, after 4,000 years of intermittent exploration, the full extent of this water-formed labyrinth remains a mystery. Today, science seeks to plumb the unknown through ongoing mapping, testing, and exploration, yet with an abiding awareness of the sentiment of one of the old cave guides: "the Cave is not soon to give up its last, deepest secret."

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• Explore the Big Woods, one of the few remaining stands of old-growth timber in Kentucky.
• Stroll the Sloan's Crossing Pond Nature Trail and listen for bullfrogs, green frogs, and red-winged blackbirds among the cattails.
• Take one of the two ferries across the Green River. The Green River Ferry and the Houchins Ferry are among the few operating rural ferries left in the nation.
• View sublime geologic artistry deep in the Earth, on the Travertine Tour.