A fire at a pier on the Chao Phraya river damaged three electric tour boats moored there for recharging, in Phra Pradaeng district on Tuesday morning.
The fire was reported about 7.20am.
The pier is rented by Mine Mobility Research Co, which offers charging services for electric boats.
A security guard said the fire started when the battery on one tour boat exploded. The flames spread to several other boats nearby, he said.
Five fire trucks were sent to fight the blaze, which was put out in about 30 minutes.
Total damage was still being assessed. There were no injuries.
The Marine Department said later that when the fire broke out there were 11 electric tour boats moored at the pier. Three of them were damaged.