The Chilean navy said the entire MS Explorer finally slipped beneath the waves Friday evening, about 20 hours after the predawn accident near Antarctica's South Shetland Islands.
No injuries were reported although passengers reportedly endured subfreezing temperatures for several hours as they waited in bobbing lifeboats for a Norwegian liner that took them to a Chilean military base in the region.
"The ship ran into some ice. It was submerged ice and the result was a hole about the size of a fist in the side of the hull so it began taking on water ... but quite slowly," said Susan Hayes of G.A.P. Adventures of Toronto, which owns the stricken MS Explorer. "The passengers are absolutely fine. They're all accounted for, no injuries whatsoever."
Throughout the day, Chilean aerial photographs showed the ship listing heavily, its white superstructure and red hull starkly visible against the gray, choppy waters and overcast skies. The navy eventually lost sight of the ship and wreckage indicated it had gone under completely, according to a navy press officer who declined be identified in accordance with department policy.
"Our units in the area aren't seeing anything," he said by telephone. "The Explorer is not visible any longer."
Hayes said 91 passengers had been aboard, including at least 23 Britons, 17 Dutch, 13 Americans and 10 Canadians. The ship also carried nine expedition staff members and a crew of 54.
The group calmly abandoned ship when the captain's order came and pumps helped keep the ship stable for an orderly evacuation, Hayes said.
Arnvid Hansen, captain of the Norwegian liner Nordnorge, said his ship ferried the passengers and crew to a Chilean air force base on King George Island in Antarctic waters near southernmost South America.
"The rescue operation ran very smoothly," the 54-year-old captain said by shipboard telephone from the Nordnorge.
GAP Adventures is a tour company that provides excursions with an environmental focus. The Explorer was on a 19-day circuit of Antarctica and the Falkland Islands letting passengers observe penguins, whales and other wildlife while getting briefings from experts on the region.
Traveling to Antarctica is always risky, Hayes said.
"There is ice in the area. Obviously it's a hazard of the area. But it's highly unusual (that the ship would hit the ice). This has never happened to us," he said.
An Argentine rescue and command center received the first distress call at 12:30 a.m. EST Friday from the Explorer amid reports it was taking on water despite efforts to use onboard pumps, said Capt. Juan Pablo Panichini, an Argentine navy spokesman.
A navy statement said that the captain ordered passengers to abandon ship about 90 minutes after the first call and that passengers and crew boarded eight semi-rigid lifeboats and four life rafts, with the captain leaving the ship later.
A Chilean ornithologist identified as Paola Palavecino was quoted in an Argentine media report as saying she and others aboard went into the lifeboats before dawn and endured subfreezing temperatures for a few hours until they were picked up about 6 a.m. EST.
"The ship took on water quickly," she was quoted by the Argentine news agency Diarios y Noticias as telling a local radio station in a call from the Nordnorge.
A commander at Chile's air base on King George island confirmed late Friday that the Nordnorge had arrived in a bay near the base, but said waves and strong winds had prevented the passengers from immediately disembarking.
He said Chilean air force planes, weather permitting, would fly the survivors on Saturday to Punta Arenas at the southernmost tip of Chile.
An Argentine navy statement said the Explorer was about 475 nautical miles southeast of Ushuaia, the southernmost Argentine city and a jumping-off point for cruise ships and supply vessels for Antarctica. Seas were calm and winds light at the time of the accident, officials said.
Last Feb. 1, the Nordnorge evacuated 294 passengers, including 119 Americans from a sister Norwegian cruise ship, the MS Nordkapp, which ran aground off a remote Antarctic island. The Nordkapp later pulled off the rocks under its own power and authorities said those passengers were never in danger.
Associated Press writer Rob Gillies in Toronto contributed to this report.