Trapped explorers led out of Mexican cave
Flash flood trapped six British explorers
CUETZALAN, Mexico (CNN) -- British Royal Navy divers on Thursday led to safety all six explorers trapped in a warren of caves in eastern Mexico.
Over several hours, the men swam out of the cave one at a time. They had been trapped in the flooded cave for a week.
Each emerged in apparent good health and spirits, officials said.
The men were to be taken to a nearby military hospital to be checked out.
They are also to be interviewed by immigration officials because they entered on tourist visas and didn't notify the Mexican government about their expedition, officials said.
A source with the British embassy said the entire expedition group is to fly back to London on Friday.
Among the cavers were four members of the British navy.
British authorities said the men were developing teamwork skills by exploring the cave complex, which covers some 38 square miles (100 square km), near the town of Cuetzalan.
With the divers' help, Chris Mitchell was the first to emerge from caves after traversing a tunnel 100 yards long and 6 feet high that was filled with water.
The navy divers arrived at the site Wednesday, accompanied by representatives of the British Embassy in Mexico City.
The underground saga has had an impact in high places. On Wednesday, Mexican President Vicente Fox -- traveling in Honduras -- expressed irritation at the presence of the British military.
Fox said the team had entered Mexico on tourist visas and failed to notify the Mexican government that some were members of the British military and that they were going on an expedition.
"I have instructed the foreign relations minister to file a formal protest immediately and to request a clarification from the British government what were they doing here," Fox said.
In London, British Ministry of Defense spokesman Paul Sykes denied Thursday that the explorers lacked the necessary authority to enter Mexico or the caves.
"We don't allow adventurous training like this ... without completion of a clearance procedure," he said in a phone interview. "And that's done before they go."
He added, "We are very clear, in our own minds, that the necessary liaison did take place and clearance procedures were completed."
Sykes said officials at the Foreign Office in London discussed the situation Thursday with Juan Jose Bremer, Mexico's ambassador to Britain.
The press attaché for Bremer said the ambassador had asked for information about what the men -- all British nationals -- were doing in Mexico.
Steve Whitlock, leader of the expedition, has said the cave structure may be among the world's longest and that the group is trying to map it for the Royal Geographical Society of Great Britain.
The expedition set off March 16 on what was to have been a two-day trip. When flash floods cut off their exit the next day, they went to a prepared underground camp that was stocked with food, sleeping bags, a first-aid kit and a radio.
CNN's Melissa Gray and Harris Whitbeck contributed to this report.