Spanish nationals David Hernandes Gasulla and Martha Miguel, Hong Kong citizen Tommy Lam Wai Yin, and Armilla Alihassan of Malaysia were on a May 2nd island-hopping excursion off the Malaysian state of Sabah on Borneo when their ordeal began.
Lam, who runs a small resort, and his intern Armilla took the vacationing Spaniards on a tour of island caves and corals when sudden strong waves capsized their motorboat.
Although they flipped it back over, they lost their drinking water and torch lights, had no food, and their mobile phones were apparently ruined, Lam told AFP in a phone interview from Sabah's capital Kota Kinabalu.
As the days wore on without rescue, they subsisted mainly on flying fish that landed in their boat, said Lam, 44.
"I will never eat sashimi for a long time," he joked.
"It was very bad, but I enjoyed it because I was so hungry."
For drinking water, they licked droplets condensing on the outside of a plastic bag of seawater left in the sun, which Miguel had seen in a movie.
But their ordeal could have ended on day one - Armilla's phone was protected in a plastic bag, which they only discovered afterward.
"We don't blame her. She was in shock," Lam said.
Malaysia's coast guard and navy launched a search-and-rescue operation but Lam said they were looking to the north, near the disputed Spratly Islands, while their stricken boat drifted nearer to Borneo.
The first few days were tense, as they angrily "blamed god, and everything under the sun and moon," for their predicament, Lam said.
Later, they became philosophical, engaging in marathon discussions on mortality.
Many boats passed nearby but either failed to spot them or did not help, as the castaways desperately used the glass of their mobile phone screens to reflect sunlight as a signal to ships.
Once, Lam saw land in the distance and desperately jumped in to swim for it, but quickly returned when the Spaniards said they had spotted sharks.
Lam said he suspects that was a lie but it may have saved his life as he was too weak to make it to shore.
After 10 days, they were picked up by two Vietnamese fishing boats trawling illegally in Malaysian waters, who took "good care" of them, Lam said.
He got their contact details and plans to personally deliver to them a 50,000-ringgit ($12,413) reward his family had offered. After a day on the trawlers, the bedraggled survivors were transferred to
Malaysian coast guard vessels and brought Friday to Kota Kinabalu for medical attention. All were weak but in good condition.
"After I returned home, the first thing I did was eat - and I ate a lot," said Lam, who celebrated his 44th birthday on Monday.
"This is my best birthday."