It's almost like a scene from a science-fiction extravaganza - a tiny figure in dark silhouette slowly descends into a vast abyss of blue ice.
The only illumination is the light from her headlamp and a sliver of pale sky. The sole lifeline is the slim rope from which she dangles, twirling ever so slightly. The crevice is the entry into the mysterious, dangerous, seemingly alien world of an ice cave in Greenland.
It's just one of the many caves exquisitely documented in MacGillivray Freeman Films' new "Journey Into Amazing Caves," now playing in (or coming soon to) Imax theaters around the country.
The film, narrated by Liam Neeson and featuring songs from The Moody Blues, follows the quest of two women, part of a burgeoning breed of "extreme scientists," to penetrate some of the Earth's last unexplored frontiers, from the caves of Greenland's massive polar icecap to forbidding underwater caves deep in the jungles of Mexico.
But for microbiologist Hazel Barton and Nancy Aulenbach, a second-grade school teacher and rescue specialist, caving reflects not only thrill-seeking adventure, but a passion for saving lives.
In each cave the duo visits, often in the company of other scientists and cavers, they collect specimens of "extremophiles."
These microscopic creatures have developed unique systems for survival in the extreme conditions of remote caves, many of which were formed millions of years ago. Scientists say they believe many of these microorganisms, with their potent chemical compounds, could contain the secrets of scientific breakthroughs.
"I go deep into the earth in search of unknown cures," Barton says simply.
The footage is extraordinary, not only of the astonishing caves themselves, but of the journeys along the way, which include MacGillivray Freeman's trademark visceral thrills - kayaking through rapids, rappelling over steep cliffs through waterfalls, and helicoptering through canyons. Those who don't enjoy roller-coaster type effects might have a queasy moment or two.
But the heart of the film is the extraordinary courage, spirit, and thirst for knowledge that drives Aulenbach and Barton in their mission.
Aulenbach doubts that she'll ever give up her explorations, "I'm always caving in my heart," she says.
(c) Copyright 2001. The Christian Science Monitor