A rare calm in Antarctic seas and the swift response by a passing ship helped save all aboard a Canadian cruise liner that struck an iceberg in the night and sank off Antarctica, rescued passengers and experienced sailors said. The MS Explorer, a Canadian-operated cruiser built in 1969 as a pioneer among rugged go-anywhere tourist ships that plied waters from the Amazon to the Arctic and Antarctic circles, struck ice Friday, took on water and dipped beneath the waves more than 15 hours later. All 154 passengers and crew spent hours bobbing in life rafts on chilly seas before a Norwegian cruise ship plucked them up shivering but safe and took them to two military bases on King George Island for flights out. A Chilean air force plane flew the first 77 survivors to the South American mainland Saturday from the island, 660 miles (1,100 kilometers) south of here. The rest were to be flown out Sunday.