10 best places to explore the underworld
Fun goes underground with these 10 subterranean adventures. We've scoured the Earth for tunnels, caves, buried neighborhoods, and other treasures hidden beneath mountains, prisons, and even thriving cities. So go ahead and skip the sunscreen—you're going underground.
Waitomo Glowworm Caves
Waitomo, New Zealand
You: in the dark, on a boat, admiring a twinkling sky. Sounds nice, right? But there's a memorable twist: You're deep underground and those aren't stars, they're living lights—the famous glowworms of Waitomo Caves in New Zealand. The worms, and the experience, are unique to New Zealand. In addition to the boat ride through the Glowworm Grotto, tours of the Waitomo Glowworm Caves include a stop at the Cathedral, a soaring cavern renowned for its acoustics.
(Photo: Wikimedia Commons via CC Attribution/Share Alike)
Puerto Princesa Underground River
Puerto Princesa Subterranean River National Park, Philippines
Float down this underground river on a raft of superlatives. The Puerto Princesa Underground River in the Philippines is not only reputed to be the longest navigable underground river in the world, but it also flows through one of the world's most impressive cave systems. This UNESCO World Heritage site was just voted one of the New 7 Wonders of Nature for its "mountain-to-sea" ecosystem that features old-growth forests, caverns full of remarkable rock formations, and the tidally influenced river that empties into the South China Sea. In order to preserve the cave, all visitors must secure a permit before entry. There's a limit to the number of people who can visit daily, so be sure to book a spot on a tour in advance.
(Photo: The Underground Tour)
It's perfectly fitting that in this tech-centric city, there was once a Seattle 1.0. In the city's first version of itself, mud—so deep it consumed dogs and children—was the primary feature. But when the Great Fire of 1889 wiped out 25 blocks, the city had to start again. Seattle used its reboot wisely, building retaining walls and raising the streets above their previously muddy foundations. Much of the original city sits undisturbed under the neighborhood around Pioneer Square, and you can explore it on Bill Speidel's Underground Tour. The quirky trip covers blocks of subterranean passageways that were once sidewalks and storefronts on a tour peppered with anecdotes and local trivia.