The seven missing US tourists whose boat capsized in the Gulf of California may still be alive due to the warm, calm waters, Mexican rescue authorities say.
Mexican Navy, army and state officials decided to keep searching over an extended area after meeting late on Monday, amid reports they would call off rescue efforts, AP reported.
One American has been confirmed dead in the accident, which came after a flash storm upended the boat before dawn on Sunday, spilling dozens of tourists and crew members into the water.
By early Monday, 19 of the tourists and all 16 crew members had been picked up by the navy or other fishing boats after clinging to coolers, rescue rings and life vests for more than 16 hours.
Mexican Navy Captain Benjamin Pineda Gomez said that, with the warm weather and water temperature in the Gulf of California, it was still possible that the missing tourists were alive.
"A person who casts away can survive many days. That sea is calm," he said.
The US Coast Guard offered Mexico help in the search and rescue operation and said it would continue its operations.
The 35-metre vessel, the Erik, sank about 100 kilometres south of the port of San Felipe early on Sunday, the second day of a week-long vacation fishing trip the group had organised for several years each Independence Day holiday.
The boat capsized less than three kilometres from shore, but the navy extended its search 100 kilometres deeper into the gulf later Monday after searching the area by helicopter and plane and finding nothing, Captain Pineda said.
Most of the 27 men on the fishing excursion are from Northern California and had made the trip before.
"I'm beyond concerned," said Kristina Bronstein, who is engaged to missing tourist Mark Dorland of Twain Harte, California.
She heard about the accident on Monday morning from a trip organiser's wife, who told her Mr Dorland, 62, was one of the first people to fall into the water. He was not wearing a life vest.
The couple are due to be married next month.
Local police officer Charles Gibson said people on the boat were awoken by other passengers and the crew as it began to sink.
Most "were in the water for over 16 hours", said Gibson, who had gone on the fishing trip twice before. "We hope that the information is getting to our families that we are here and that we survived."
Another survivor, Lee Ikegami, called his wife in San Martin, California, and told her he survived by clambering into a life raft when the boat overturned.
"There was an angel sitting on his shoulder," his wife, Murphy Ikegami, said.
Murphy Ikegami said the fishermen made the trip every year but would only make day trips out to sea to fish and stayed in hotels along the coast at night. This year, she said, they decided they wanted to sleep on the boat.