Clelia-II-Antarctica-Engine-Failure Update, December 10, 7:15 a.m. EST: The International Association of Antarctica Tour Operators (IAATO) confirmed to The Weather Channel that Clelia II arrived safely back in Ushuaia Thursday night.

Update, December 8, 3:30 p.m.: According to a release issued by the International Association of Antarctic Tour Operators (IAATO), Clelia II is now operating at normal speed during its northbound crossing of the Drake Passage. Fred DeSousa, a spokesperson for Travel Dynamics (the ship's operator), told Cruise Critic that it was expected to arrive in Ushuaia late Thursday night or early Friday morning. The next scheduled cruise, which was set to embark today, has naturally been canceled. DeSousa said the impacted passengers have been flown home and that the ship will be ready for its December 17 departure. The IAATO release added that Clelia II is carrying 88 passengers, all of which are from the United States, and 77 crew. One clarification: the ship, which is operated by New York-based Travel Dynamics International, was chartered to Grand Circle Travle. It is not operated by Polar Cruises as originally reported.

(10:30 a.m. EDT) -- News outlets are reporting that an expedition cruise ship returning from Antarctica suffered engine failure yesterday due to rough weather but is now crawling back to its Argentinean homeport under its own power.

The Herald Sun said Polar Cruises-operated Clelia II ran into trouble on Tuesday afternoon while transiting the Drake Passage and was experiencing what the Argentine navy termed "serious handling limitations."

According to the Herald Sun, the crew was later able to fix the problem. The Argentinean Navy told the Associated Press that the ship, which was scheduled to return to Ushuaia today (Wednesday), is now heading for the port at 4 knots. All passengers are safe and the ship is being accompanied by an Argentine naval vessel. We're unsure of when the ship will arrive in Ushuaia.

Reports on the number of passengers and crew onboard the Clelia II have varied. The Marine Log stated that the ship, which officially carries 100 passengers at double occupancy, had 101 passengers and 65 crew. Bowermaster reported that it's carrying 88 passengers, all from the United States, and 77 crew -- and that one of the crewmembers suffered a minor injury. We've reached out to Polar Cruises for comment via e-mail and phone, but the expedition-travel operator has yet to respond.

The Marine Log is also reporting that the Argentinean Navy Search and Rescue Coordinating Center was notified of Clelia II's situation by Lindblad Expeditions' National Geographic Explorer, which was in the vicinity. The following video, which was taken by Fiona Stewart/Garett McIntosh from NG Explorer and first posted by John Bowermaster, shows the ship in distress:

This isn't the first time Clelia II has encountered issues in Antarctica. In December 2009, the ship hit rocks while preparing a passenger landing at Petermann Island, Antarctic Peninsula. On that occasion, it suffered damage to a propeller and had to be returned to Ushuaia under escort and pulled from service for repairs.

We'll keep you posted.

--by Dan Askin, Associate Editor, and Kelly Ranson, U.K. Editor