Officials from the Krabi Harbour Office on Monday joined with forensic police and related officials to inspect the scene where the Sunday explosion of a speedboat injured 16 tourists and boat staff heading from Phuket to Koh Phi Phi.
In seeking the cause of the explosion and fire, officials will interview those involved.
They were waiting to talk to boat driver Kriengkrai Boonsri, 28, who on Monday was being treated in a Krabi hospital's intensive care unit.
Minister of Tourism and Sports Weerasak Kowsurat on Sunday afternoon visited the injured tourists, identified as Xu Xin (female) and Wu Zhian (male), at Krabi Nakharin International Hospital and instructed officials to take care of the wounded and provide aid as appropriate.
Meanwhile, officials from the Trang Harbour Office, Had Chao Mai National Park and marine police checked boats at piers on the popular Koh Kradan to ensure passengers wore safety gears.
Officials also instructed boat drivers to ensure their boats were in good condition and properly equipped with safety gear before departing and to not overload the boats.
Koh Kradan has heavy speedboat traffic carrying foreign tourists from Phuket, Krabi and Phang Nga to visit the Trang Sea.
The destroyed speedboat left from Thai Morning Sun Pier in Phuket's Muang district and was headed to Phi Phi Island when it exploded on Sunday in front of the so-called "Viking Cave" popular tourist attraction.
A fuel leak was initially identified as the probable cause of the accident.
26 Chinese tourists, a Chinese tour guide, a Thai tour guide and three boat crewmembers, including the captain Kriengkrai, were on the boat at the time.
Out of the 16 people who sustained injuries, eight were seriously hurt and remain in hospital, including five Chinese tourists and Kriengkrai.