Abandoned mines can cause real problems—everything from toxic waste spills to accidental deaths resulting from falls down open mine shafts. The Bureau of Land Management has acknowledged the issue by forming AbandonedMines.gov, a group dedicated to securing the estimated 500,000 abandoned mines in the U.S. And while most of these mines, and others worldwide, will remain off limits to the public, crafty entrepreneurs are taking over a handful of these empty underground spaces and transforming them into jaw-dropping public entertainment arenas. Race through the darkness on a four-wheeler or soar through the air on an underground Ferris wheel at these five reimagined locations.

Mines and Meadows, Pennsylvania

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What once was a limestone mine that opened in the late 1800s is now a once-in-a-lifetime experience for ATV enthusiasts at Mines and Meadows. The company offers an ATV tour that takes riders into the mine, with parts lit only by the vehicles' headlights. Riders start above ground, then head into the mine’s entrance—complete with a beamed entryway—and twist and turn through the darkness of the half-mile track. At times the ceiling is so low that riders can reach up and touch it while seated on their ATVs, offering a hint of what the dark and cramped working conditions of the mine once were.

Turda Salt Mine, Romania

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The Turda Salt Mine has had various lives since it opened in the 17th century. Miners excavated salt until 1932, when nearby competing mines put it out of business. From there, Turda was used as a bomb shelter for local residents during World War II, and in 1945 when the war was ending, cheesemakers took over the space for storage. Then, in 1992, the nearby city decided to turn the mine into a theme park. Now, in addition to a museum about the mine’s history, the underground caverns holds a surreal theme park complete with a Ferris wheel, mini golf course, a lake with paddle boats, a bowling alley, an amphitheater, sports fields and ping pong tables.

Wieliczka Salt Mine, Poland

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Salt manufacturing first began at the Wieliczka mine as early as the 10th century, when medieval settlements put down their roots in the area. The first shafts for the mine itself were dug in the 1200s, and shortly thereafter the Saltworks Castle was constructed, which remained the mine's main office until 1945. Up through this point, the mine was called the Old-Polish Krakow Saltworks. At its height of production in the early 16th to mid 17th centuries, the saltwork's crew of about 2,000 people mined about 30,000 tons of the mineral each year. On June 10, 1772, after the Austrian army occupied the area, the original saltworks ceased production, reopening as the Wieliczka Salt Mine, alongside the Bochnia Salt Mine.

In 1838, the mine's physician, Dr. Feliks Boczkowski, opened the first health resort in the area, featuring underground saline baths, salt mud treatments and steam inhalations​. These treatments, and others known as subterraneotherapy, can still be experienced by visitors today at the modern Wieliczka Salt Mine Health Resort. Aside from the spa, the Wieliczka mine of today offers underground events and religious services, adventure tours, art galleries, a museum and two underground hotels.

Louisville Mega Cavern, Kentucky

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Hidden underneath Louisville, Kentucky, is an expansive cavern measuring more than 4 million square feet. It started as the Louisville Crushed Stone company, which mined limestone there for about 42 years. The cavern is so large it’s classified as a building by the State of Kentucky, with ongoing construction to build in storage spaces and offices. During the Cuban Missile Crisis, it was even slated to hold 50,000 people as a bomb shelter in case of a nuclear attack. Now, the cavern is a multipurpose space called Louisville Mega Cavern. It has storage units providing bulk warehousing needs, an events center and attractions for tourists, including underground zip lines, tram tours, a 320,000-square-foot bike park, an underground aerial ropes course, electric bike tours and an annual underground Christmas holiday lights display.

Zip World Slate Caverns, Wales

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From 1846, the Llechwedd slate quarry supplied the world with high-quality slate, shipping it from the mine by rail and boat to customers. At Llechwedd’s peak production in the 1880s, the mine employed more than 500 workers and produced more than 23,000 tons of slate annually. Demand for slate declined sharply in the 1960s, though, and the underground portions of the quarry ceased operations. But instead of letting the mine space go to waste, the company decided to turn the land into a tourist attraction, opening Llechwedd Slate Caverns tours in 1972. Now, Zip World occupies part of that space, offering subterranean zip lines, giant trampolines and aerial obstacle courses.