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.
"Misadventure can befall anybody," he said, but he added that the number of tourist ships coming to Antarctica's busiest areas was a concern.
While Antarctica is as big as the United States and Mexico combined, tourists and scientists for the most part keep to areas that aren't permanently frozen and where wildlife can be found. Those account for less than 2 percent of the continent.
It's a land of many hazards, not all of them obvious. The dry air makes static electricity a constant threat to electronics and a fire risk when refueling vehicles. Residents quickly get into the habit of touching metal fixtures as they pass, and metal discharge plates are set beside all telephones and computer keyboards.
Most tourists arrive on the Antarctic Peninsula, which is easily accessible from Argentina and Chile. The next most popular destination is the Ross Sea on the opposite side of the continent, a 10-day sail from New Zealand or Australia.
Both landscapes are intensely bright and profoundly silent during the 17 weeks between sunrise and sunset in the summer. The peninsula is a milder environment and has a wider variety of fauna and flora.
The Ross Sea, where the Royal Society Range soars 4,200 meters (13,200 feet) above the ice-clogged waters of McMurdo Sound, demonstrates the colossal grandeur for which Antarctica is renowned. It was also the starting point of British expeditions to the South Pole during the so-called heroic era of Antarctic exploration from 1895 to 1915. The early explorers' wooden huts still dot the coast.
The Ross Ice Shelf, the world's largest mass of floating ice covering an area almost as big as Spain, rises as steep, gleaming cliffs 60 meters (200 feet) from the sea.