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Mammoth Caves in the state of Kentucky in America is the world's longest mapped cave system and is blessed with fantastic limestone formations.
The best time to visit is spring (after the snow melts) and fall. In summer, temperatures soar. So do crowds, to the point where tours can quickly sell out.
Guided cave tours
You have a choice of tours, ranging from easy to expert:
The easiest tour is well lit, has strategically placed handrails, and lasts a little over an hour.
The next tour is a little harder and longer, but you see Mammoth Dome, a massive cavernous room measuring 58 meters (192 feet) from floor to ceiling.
The National Park Service offers experienced cavers a six-hour Wild Cave Tour. You don helmets, knee pads and other spelunking gear to explore unlit pathless areas. Sometimes you need to squeeze through tight passages and muddy crawlspaces.
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