Two boats carrying European and Chinese tourists collided and overturned yesterday near Koh Khao Phing Kan, also known as James Bond island, dumping about 20 people into the Andaman Sea off Phangnga, 19 of whom were injured.
Phangnga National Park officials reported the collision.
All were rescued from the water and the injured were taken to Phangnga Hospital, the park's said in a statement.
Deputy Phangnga governor Ekkarat Leesen said 19 people were hurt and needed hospital treatment.
The park and the Disaster Prevention and Mitigation office in Phangnga said one tourist was seriously injured.
The accident occurred as a long-tailed boat -- with 11 Norwegians, four Belgians, a Thai guide and three crew members on board -- was leaving the island for lunch at Koh Panyee, the deputy-governor said.
The boat collided with another vessel which was carrying an unknown number of Chinese tourists to James Bond island. No other details about the second boat were provided. No passengers from the second boat fell into the sea.
Poor visibility due to rough seas could have caused the collision, Mr Ekkarat said.
Phangnga National Park chief Sarayuth Tanthien said three of the tourists suffered cuts to their heads. Others suffered minor wounds.
An initial examination found that the two boats did not have licences and were not authorised to enter the national park. The drivers were fined 500 baht each.
Mr Sarayuth said the accident happened because the two drivers lost control of their respective boats due to strong winds.
Takua Thung deputy police chief Pol Lt Col Somkid Khaosang said the drivers of the two boats will be summoned for questioning and charged.
A source said Marine Department officials will also summon the pair.
The Meteorological Department yesterday forecast strong winds and rain in areas around Ranong, Phuket, Phangnga, Krabi, Trang and Satun. Waves are expected to be two metres high and higher in areas affected by storms.
Small boats were advised not to leave shore.