Developed high in the alleyways of New York City, ziplining originated as extreme clothesline hanging and required agility to keep pigeons from building nests in pairs of underwear. Take on this tradition with today's Groupon to Louisville Mega Cavern. Choose from the following options:

• For $43, you get an underground zipline tour with souvenir photo Monday–Thursday (up to an $86 value).
• For $48, you get an underground zipline tour with a souvenir photo Friday–Sunday (up to a $96 value).

The expert tour guides at Louisville Mega Cavern propel guests through a 4,000,000-square foot subterranean expanse, slinking in and out of more than 100 acres of man-made passageways and across three challenge bridges. Originally a limestone mine, the cavernous zipline facility utilizes its 90-foot-high thoroughfares to unite guests with an exhilaration previously known only to highly-caffeinated miners. Throughout the two-hour zipline tour, amateur spelunkers will stream across the subterrain’s five underground ziplines and dual racing lines under the sage supervision of the cavern's ACCT-certified experts. Along the way, guides will entertain guests with tales of the cavern’s rich history and uncanny impressions of stalagmites. To keep memories immune to the diminishing effects of time, tour-goers will receive a souvenir photo upon the conclusion of each excursion.