Cold saltwater hit him when the cage he was in dropped into the sea.
With more than 27kg of diving equipment, Filipino Ro Galeno, 38, descended nearly 30m onto the seabed, just 1km off the coast of Singapore's Pulau Sudong.
"Fun. The water's clear today, that's good," said Mr Galeno of the experience last Thursday.
That was not the first time he had done a commercial dive. It was just like any other that he had carried out over the past four years, repairing ship hulls and doing welding work underwater.
But the dive last week was part of a commercial diving course that Mr Galeno completed, making him one of 28 divers to be certified under a local Workplace Safety and Health (WSH) Council diving standard.
They are the first divers attaining the standard, which qualifies them for all diving work within Singapore.
Last week, The New Paper reported that many marine companies did not abide by the standard, a code of practice licensed by government agency Spring Singapore in 2005.
The lack of training options also compounded the problem.
But the WSH Council has since accredited training provider KB Associates to assess and qualify experienced commercial divers to the local standard.
Known as an assessment-only pathway (AOP) programme, it includes assessors who grade trainees according to the criteria set out by the council.
The programme is still not available to the public, but a council spokesman said a full training one will be launched in phases by next year.