The death of a man who went missing during a family outing at Sisters' Islands last year has been ruled a misadventure.
Mr Antoni, whose body was found in the waters days later, was found to have drowned.
He was likely to have been pulled into the open sea from the mouth of a lagoon where he was believed to be at, said State Coroner Kamala Ponnampalam in her findings on Tuesday.
Mr Antoni, who went by one name, had gone with his family and his brother-in-law's family to Sisters' Islands on Dec 6 last year.
The 41-year-old Singaporean later went to a lagoon to snorkel alone. He did not wear a life jacket.
About an hour later, his wife realised he had not returned and alerted her brother, who did not manage to find him.
She later approached National Parks Board officers who were in the area, but they also could not find him.
The Police Coast Guard, Singapore Civil Defence Force and Maritime Port Authority were notified, and a team of commercial divers was activated to search for Mr Antoni.
His body was seen floating at sea off Sisters' Islands two days later, on Dec 8. He was found without any snorkelling gear.
In her findings, the state coroner cited the account of an eyewitness who said he had seen someone swimming towards the mouth of the lagoon on that day.
He recounted that the waters at the lagoon were choppy with a strong undercurrent then, and that he had concluded that it was unsafe to swim in the lagoon.
State Coroner Kamala also highlighted the account of a commercial diver who went to recover Mr Antoni's body.
He said he had dived from the lagoon towards the open sea, where the undersea currents were very strong and the waters were deep.
The diver also said that snorkellers, especially non-professional ones, should wear a life jacket when they are entering the big lagoon.
State Coroner Kamala also said there were signs prominently placed near the lagoons and the breakwaters at Sisters' Islands to alert visitors to the dangers of swimming in the lagoons.
The lagoon that Mr Antoni had gone to had no barriers at its mouth to prevent a swimmer from being swept out to the open sea.
The state coroner said the movement of commercial vessels along the fairways or channels outside the lagoon would impact the undersea currents near Sisters' Islands. "The chances of someone being pulled out into the open sea if he swims close to the mouth of the lagoon is significant," she added.
Among other things, State Coroner Kamala also noted that Mr Antoni's wife had said she was unsure of his swimming ability, and that the family was unaware of the tidal stream and undersea currents near the islands.
The state coroner said leisure snorkellers must always be cognisant of their surroundings and guard against potential dangers. "Snorkelling in choppy waters or when the currents are strong is ill advised, especially so for an inexperienced snorkeller," she said.
She added that beginner snorkellers should don a life vest or a flotation aid for buoyancy. "They should also pay heed to the signage and carefully select a spot which is safe for their snorkelling activity," she said, extending her condolences to Mr Antoni's family.