"We are extremely pleased to learn that both the Xue Long and the Akademik Shokalskiy freed themselves from the ice," Coast Guard Pacific Area commander Vice Adm. Paul F. Zukunft said in a statement.
"This case underscores the dynamic and harsh operating environment and the necessity for polar-class icebreakers in the antarctic," he said.
"I am indebted to the tremendous collaboration with RCC Australia, other countries that assisted and the National Scientific Foundation throughout this operation," he said, referring to the Australian Maritime Safety Authority's Rescue Coordination Center.
Agencies from France and Germany were also involved in the rescue operation, the Australian agency said.
The two trapped ships reported breaking free of the ice about 30 minutes apart.
Igor Kiselev, the Akademik Shokalskiy's captain, told the Australian agency he and his crew were able to free the 233-foot ship, which was trapped in thick ice off Antarctica for two weeks, after cracks formed in the ice, the maritime agency said Wednesday.
His vessel is now headed to Bluff, New Zealand's southernmost town, the agency said.
"We continue to sail northward, changing courses and speed. The speed is 7 knots," or about 8 mph, Kiselev told Russia's official ITAR-Tass news agency.
Chinese-flagged icebreaker Xue Long, or Snow Dragon, which got stuck trying to release the Akademik Shokalskiy, broke free after doing a 100-degree turn and pushing away the ice, said the maritime agency, which coordinated the two-week rescue effort.
The Akademik Shokalskiy became trapped in ice up to 17 feet thick in Antarctica's Commonwealth Bay Christmas Eve. It originally had 52 passengers -- scientists, graduate students, journalists and tourists -- and 22 crew members on board.
A helicopter from the Snow Dragon ferried the passengers to Australian icebreaker Aurora Australis last week.
The passengers are now on their way to Hobart, Australia, the Tasmanian capital, aboard the Aurora Australis after the icebreaker stopped for fuel and supplies at an Antarctica base, the Australian Broadcasting Corp. reported.
Coast Guard icebreaker Polar Star was speeding at full throttle to Antarctica from Seattle, but the stranded ships broke loose before it arrived.
The ship will now proceed on its original mission, to break up the ice-clogged waters of Antarctica's McMurdo Sound near the Ross Sea, about 930 miles away, the Coast Guard said.
Its job is to break a channel through the ice so supplies and fuel can be transported to the National Science Foundation's South Pole U.S. Antarctic Program research stations, Polar Star Capt. George Pellissier said.