The rhythms of life on Sipadan Island, in eastern Malaysia, were measured, until two days ago, by the plop of scuba divers vanishing beneath the surface of crystal waters.
Tourists still lounged on the island's sugar-white sands yesterday, and snorkelled in the waves, home to turtles, sharks and barracuda. But in an incongruous addition to an otherwise idyllic scene, a policeman with an M-16 rifle stood guard on a jetty and a naval gunship was anchored 500 yards off shore.
The tropical serenity so prized by visitors to Sipadan, a world-renowned dive centre 20 miles off the coast of Sabah state, was shattered on Sunday night when six armed gunmen stormed one of its resorts and abducted 21 people including 10 foreign tourists.
An air and sea search by Malaysian and Philippine military forces failed to locate the captives yesterday, while militant Philippine Muslim guerrillas claimed responsibility for seizing them.
The claim by the Abu Sayyaf group has yet to be verified and was withdrawn by the rebels themselves a few hours after it was made, in an apparent attempt to sow confusion.
If true, it would mean that the group - three Germans, two French nationals, two South Africans, two Finns and a Lebanese tourist, all guests at the Pulau Sipadan Resort, plus nine Malaysians and two Filipino resort workers - have become caught up in a lethal game of geopolitics and sectarian extremism.
Sipadan, a 30-acre coral speck considered one of the world's top 10 dive sites, is a 45-minute boat ride from Philippine waters and is also near the Indonesian border.
A source close to Abu Sayyaf, which is fighting for an independent Muslim state in the mainly Catholic Philippines, said that the hostages were being held in the Tawitawi group of islands, in Sulu province, an hour from Sipadan. A Philippine police intelligence report confirmed the location.
The same rebel group has been holding hostage 27 Filipinos, mainly schoolchildren, on the southern island of Basilan, 275 miles across the Celebes Sea from Sipadan, for the past month. It claimed last week to have beheaded two male teachers.
Abu Sayyaf is demanding the release from jail in the US of two Muslim militants, including Ramzi Yousef, mastermind of the bombing of New York's World Trade Centre in 1993. Philippine government forces launched a massive assault on Abu Sayyaf's mountain stronghold on Basilan, killing 20 rebels, on the day the tourists were abducted.
The six kidnappers, who were armed with AK-47 assault rifles and a rocket launcher, captured everyone they encountered on their way to the dining room in the Sipadan resort, made them swim to two fishing boats and then headed out to sea.
An American couple, Mary and James Murphy, who managed to escape, were counting their blessings in Kuala Lumpur yesterday. "I was there to scuba dive," said Mr Murphy, 51. " It could happen to anyone on holiday." The events have sent a shudder through the Malaysian tourism industry, the country's third-biggest foreign revenue earner. The Prime Minister, Mahathir Mohamed, sought to reassure foreign visitors that other parts of Malaysia were safe.
Eight million tourists visit Malaysia every year, and 400,000 of them go to Sabah, on the northeastern tip of the island of Borneo.tourism was crippled on the Indonesian island of Lombok, near Bali, earlier this year by ethnic violence.
Sipadan, so small that it can be circled on foot in 20 minutes, rises sharply for 2,100 feet above the seabed, which is so rich in coral reefs, sponges and anemones that it has been likened to an aquatic rainforest. The abundant sea life includes black-tip sharks, moray eels and clownfish. Leatherback turtles lay eggs on the beach during the breeding season.
The region is also infested with pirates, who, if Abu Sayyaf's claim proves to be an empty boast, are the other possible culprits.
Semporna, the Sabah port town from which boats leave for Sipadan, was attacked by pirates three times in 1996. Pirates attacked the neighbouring coastal town of Lahad Datu in 1995, killing 11 people.
Malaysian navy vessels and marine police boats patrolled international waters yesterday, while police helicopters and Air Force planes searched overhead. In the Philippines, two naval gunboats and a reconnaissance plane scoured the southern coastlines
Five people were arrested in Sabah, and were said by police sources to include former workers at the Pulau Sipadan Resort, who had connections to the local fishing community and were suspected of facilitating the abductions.
Although the resort has been cleared and the island declared off-bounds, tourists remain at the other resorts.