Panyawut Phothong, 26, and another injured crewmember were rushed to Khao Lak Hospital after being severely injured in the blast on the Kalamung Dee 2 on Tuesday night, but Panyawut died on Wednesday morning, police said.
Another worker, Aroon Chanpaksuan, 25, remains in the hospital, they said.
The vessel was docked at a pier in the province’s Muang district when the explosion occurred at about 9pm on Tuesday.
The blast happened in a toilet at the front of the vessel, police said.
The speed boat, which took tourists on tours of the Similan Islands, was docked at a pier in
Thap Lamu village in Lam Kaen tambon when the blast occurred.
The ensuing fire prompted the crews of other boats docked nearby to steer them away.
Rescue officers from Phang Nga Naval Base district joined district and tambon officials to extinguish the fire, said Siwat Rawangkul, chief of Muang district.