The head of the Tanjungpinang SAR Office section, Eko Supriyanto, explained that the incident began when the unidentified victim went fishing on a boat in Bakong Island waters around 14.00 local time.
Suddenly the boat was overturned by a wave, so the victim fell into the sea and sank.
"We obtained information about the sea accident from Saljuan, one of the local fishermen this afternoon," Eko said.
After receiving the information, he continued, the SAR Standby Rescue Unit Team went straight to the scene at around 17:30 local time.
The search also involved the Tanjungpinang SAR Office, the Lingga water police and fishermen around.
"The search for victims still continues to this day," Eko added on Sunday night.