The Svalbard archipelago, just 670 miles from the North Pole, is the most accessible gateway to true arctic wilderness. This unforgiving Norwegian frontier has long attracted husky-sledding expeditions, kayaking cruises, and snowmobiling safaris. But it's the mercurial freeze-thaw cycle of its gargantuan glaciers that draws the attention of ice cavers, who come here to burrow into the freeze rather than slide across its glassy surface.
Caving expeditions – like pretty much everything in Svalbard – begin in Longyearbyen, the archipelago's main settlement and the northernmost town on Earth with more than a thousand residents. Home to 2,000 extremely hardy types (largely descendants of Norwegian and Russian coal miners), the rainbow-colored town shivers on the shores of Adventfjorden like a blizzard-blitzed Legoland. Not far off, Longyear Glacier slides imperceptibly, slowly down snow-covered Sarkofagen Mountain.
Spelunkers make the frigid commute on snow cats, fully tracked muscle tanks that grind up the mountain valley as their passengers, head gear muffling the sound, jostle peacefully in the cabin behind. The guides up front carry powerful guns. The islands of the archipelago are home to 3,000 polar bears, the only mammal known to actively seek humans for food. After arriving at the mountain ridge, adventurers make a frostbitten dash into a small man-made igloo, freshly hewn into the glacier's surface. Inside, the gateway to the underworld is a small bored-out hollow that looks more like an air hole than an actual entrance. After a good deal of strapping in – helmets, headlamps, gripped snowshoes, rappelling racks – cavers rappel down the narrow shaft into the chamber below. Then the journey begins in earnest.
Routes formed by meltwater streams coursing through the ice – given the all clear by a local glaciologist – shift depending on the year's melt but always remain unearthly and serene. Stalactites hang like diamond cutlasses over crystallized caverns, and pitch-black passages suddenly and forcefully reflect torchlight. Tiptoeing along pulley leads and crawling on all fours, spelunkers navigate the labyrinthine glacier for up to five hours, keeping warm by expending their energy sliding and crawling.
Several hundred yards and a lot of frozen breaths later, it's time to climb back toward the surface, check for bears, and make the sprint to the waiting snow cat. Temperatures may plunge beneath -35 degrees, but sweat – cold and warm – seeps through everyone's long underwear.
More information: Ice-caving excursions cost $120 with adventure outfitter Spitsbergen Travel. Longyearbyen can be reached via a four-hour flight from Oslo with SAS Airways ($380). The town's sparse accommodation options are nothing if not diverse, varying from the world's northernmost campsite to a Radisson that just so happens to be the world's northernmost hotel (rooms from $220). While at the ends of the Earth, be sure to join the after party at Huset, perhaps the world's only nightclub where you check your snowsuit at the door.