ROSS ISLAND, Antarctica (AP) -- Across most of Earth, a tourist attraction that sees 35,000 visitors a year can safely be labeled sleepy. But when it's Antarctica, every footstep matters.
Tourism is rebounding here five years after the financial crisis stifled what had been a burgeoning industry. And it's not just retirees watching penguins from the deck of a ship. Visitors are taking tours inland and even engaging in "adventure tourism" like skydiving and scuba diving under the ever-sunlit skies of a Southern Hemisphere summer.
In a remote, frozen, almost pristine land where the only human residents are involved in research, that tourism comes with risks, for both the continent and the tourists. Boats pollute water and air, and create the potential for more devastating environmental damage. When something goes wrong, help can be an exceptionally long way off.
The downturn triggered by the economic meltdown created an opportunity for the 50 countries that share responsibility through the Antarctic Treaty to set rules to manage tourism, but little has been done. An international committee on Antarctica has produced just two mandatory rules since it was formed, and neither of those is yet in force.
"I think there's been a foot off the pedal in recent years," said Alan Hemmings, an environmental consultant on polar regions. "If it takes five years, 10 years to bring even what you agree into force, it's very difficult to micromanage these sorts of developments."
Antarctic tourism has grown from fewer than 2,000 visitors a year in the 1980s to more than 46,000 in 2007-08. Then the numbers plummeted, bottoming out at fewer than 27,000 in 2011-12.
The Rhode Island-based International Association of Antarctic Tour Operators doesn't have its final figures yet for the 2012-2013 season, which runs November to March, but estimates close to 35,000 visitors. The industry group expects slightly more tourists next summer.
It's not just the numbers of tourists but the activities that are changing, said Hemmings, who has been part of a delegation representing New Zealand in some Antarctic Treaty discussions.
"What used to be Antarctic tourism in the late '80s through the '90s was generally people of middle age or older going on cruises and small ships where they went ashore at a few locations and they looked at wildlife, historic sites and maybe visited one current station," he said. "But there's an increasing diversification of the activities now so it's much more action orientated. Now people want to go paragliding, waterskiing, diving or a variety of other things."
Visitors can also skydive over the frigid landscape, and London-based Henry Cookson Adventures took two and three-man submarines to Antarctica in the latest summer. Hemmings said he was once asked to advise on a Germany company's plan to fly gliders over the colossal Transantarctic Mountains to the South Pole, but that project was never carried out.
On Ross Island, a stark black-and-white outcrop of ice on porous, volcanic rock, the active volcano Mt. Erebus stands as a warning of the dangers of tourism in this remote and hostile environment. In 1979, an Air New Zealand airliner on a sightseeing tour from Auckland slammed into the mountain in whiteout conditions, killing all 257 people aboard. After that disaster, sightseeing flights over Antarctica did not resume until the mid-1990s.
Some of the earliest attempts at skydiving in Antarctica also ended in tragedy. Two Americans and an Austrian died in the same jump in 1997 near the U.S. Amundsen-Scott South Pole Station at the geographic South Pole.
Hypoxia -- a lack of oxygen -- is a suspected reason why the skydivers failed to deploy their parachutes in time. Antarctica is not only the world's coldest, driest and windiest continent, but also the highest. The South Pole is on an icy plateau 2,835 meters (9,301 feet) above sea level and the air is relatively thin.
The last fatalities at sea near the continent were in February 2011, when a Norwegian-flagged, steel-hulled yacht with three crew vanished during wild weather in the Ross Sea.
It's not only tourists who get into trouble. Searchers will wait until at least October to recover the bodies of three Canadians involved in scientific research who died in a plane crash in January near a summit in the Queen Alexandra range. A fire aboard a Japanese whaling ship in the Ross Sea killed a crew member in 2007. And anti-whaling activists lost a boat that collided with a whaler in 2010. No one was injured.
Hemmings said tourist ships have been involved in several mishaps in Antarctica in the past five years.