Colonel Dr Pak Loharachun, the commander of Medical Battalion, Nakhon Ratchasima, arrived at the Tham Luang cave in Mae Sai district on Friday.
He will be among members of three SEAL groups on standby to dive towards the Pattaya Beach section of the cave.
A SEAL team is preparing necessary equipment and guided line to enter the location in preparation for the three SEAL teams.
It is reported that the doctor is certified in special courses including special operations, SEAL, commando, airborne delivery and reconnaissance.
The missing group has been trapped inside the cave since June 23 after a flash flood hit the area, hampering them from leaving the cave.