At these caverns you can descend 500 feet on Britain's deepest underground railway to a mine where you walk by an eerie underground lake. Here Victorian working conditions have been re-created, and the tour gives a good idea of the difficult lives the miners had to endure. Above are a re-created Victorian village and slate-splitting demonstrations. Thrill-seekers will enjoy the hair-raising 5-mile zip line, where you can reach speeds of up to 70 mph; visit www.zipworld.co.uk for more information. There's also a new underground trampoline playground for young children. Wear sturdy footwear when visiting the mine—during busy times you may have to climb 70 steps as part of the tour.