Ni Minghao, 38, who run a travel agency in Phuket, said the weather was fine on Thursday morning, but a storm arrived suddenly in the afternoon, bringing strong winds and waves. Since it is summer vacation, there were many children on the boats.

Noraphat said on his Twitter social media account early Friday morning that 53 people were missing from the Phoenix dive boat, which was carrying 105 passengers and crew. The boat sank near Koh Heh and most of the missing passengers were Chinese tourists, he said.

All 41 passengers and crew on the yacht Sereniga, which went down between Koh Heh and Koh Mai Thon, have been rescued, Noraphat said.