If the phrase "subterranean palace" piques your curiosity, consider paying an exploratory visit to North Chungcheong Province's Gosu Cave. Across the river from Danyang, this sizable limestone cavern descends 1,298 m (4,259 ft) into the Earth's crust, displaying five and a half kilometers of incredible stalactite and stalagmite formations that can't help but leave an impression. Though the path for visitors only covers about 1/3 of the total length, it's more than capable of eliciting a few "oohs" and "ahhs" via unique geological figures like Lion Rock, Octopus Rock and the Virgin Mary rock itself. Remember to bring something long-sleeve (the interior of Gosu stays an unwavering 15°C year-round), and be prepared for a few fairly tight spaces and more than a few stairs. All in all, though, that's a small price to pay for such a memorable experience.
Location:Danyang-gun, South Korea
Note:This one goes out to all you history buffs out there: prehistoric stone artifacts unearthed near Gosu Cave's entrance back in the 1970's indicate its ties to early South Korean civilization, making a visit to this national monument an excursion into both the country's natural and ancestral past.