Top 10 Extreme Travel Adventures
Rappel down the side of a limestone cliff, squeeze through damp crevices covered with luminescent glowworms, leap from a subterranean waterfall, and go "black-water rafting" in the underground rapids at Ruakuri Cave, part of the otherworldly Waitomo cave system in New Zealand. The five-hour Black Abyss travel adventure offered by The Legendary Black Water Rafting Co. (www.waitomo.com/black-water-rafting) is the most challenging of the region's guided extreme travel tours, with a mix of climbing, rappelling, and cave tubing.
Low-Adrenaline Alternative: For a less-demanding domestic descent, go to Carlsbad Caverns National Park (www.nps.gov/cave) in southern New Mexico. Rather than rivers and waterfalls, the 300 caves here were carved out by limestone-dissolving sulfuric acid, making for a much drier – yet still "deeply" satisfying – experience.