A body believed to be that of a 24-year-old Vietnamese national reported missing on Monday was found floating in the sea early on Tuesday off East Coast Park.
The body of Tran Huy Tho was spotted by a relative who had flown in from Ho Chi Minh City after learning of his plight.
He was just a few metres from the spot where he had last been seen by two friends who were at the park with him on Monday.
Mr Tho, who had been in Singapore for four years, told the pair he wanted to go swimming by himself near a breakwater, in an area marked as a no-swimming zone.
According to one of his friends who identified himself only as Mike, a finance student at the Management Development Institute of Singapore, Mr Tho "sat on the rock and then suddenly jumped, swam about 30m, and then disappeared" around noon.
They alerted the police shortly after and a search was conducted, but there were no signs of Mr Tho.
The friends also contacted Mr Tho's family in Hanoi, and his cousin Tracy Nguyen, 26, took an afternoon flight to Singapore.
Speaking to The Straits Times on Tuesday, Ms Nguyen said she immediately rushed to the park upon arrival on Monday evening, but retreated when darkness fell.
It was only after she returned to the area where he had jumped into the water at around 7am on Tuesday that she spotted his body floating nearby, and called the authorities.
Police have classified the case as an "unnatural death", and said investigations are ongoing.
Ms Nguyen is fairly certain her cousin killed himself.