Su begged his family's forgiveness for taking on the task, and said he hoped his belongings will be handed to his next of kin if he failed to return. 

On Sunday afternoon, the Ram Union team first mapped the 20 kilometers around the capsized boat, with a sophisticated sonar device. The equipment will help find debris and possible victims, He said. 

Divers who entered the wreck on Saturday described heartbreaking scenes of bodies of children found in the arms of their mothers. China Daily was unable to get in touch with the official Chinese team as of press time.

Thai rescuers' search efforts paid off when they picked up from the water Tan Xinyan, 25, on Friday morning.

"I was lucky enough to be rushed out from a broken window," the woman told Beijing News on Saturday. 

Local authorities said on Sunday that the two captains have been charged with negligence resulting in death and physical and mental harm to others.

Chinese Ambassador to Thailand Lyu Jian told reporters on Sunday that the search work for the missing will continue until all are found and Chinese authorities and experts will participate in the investigation into the accident launched by Thai authorities.

Contact the writers at houliqiang@chinadaily.com.cn