This boat was on a fishing expedition when it capsized off the southern coast of South Korea.
At least eight people have died.
Three others have been rescued and are recovering in hospital.
The coast guard's searching for several people still missing.
Authorities say the boat lost radio contact late on Saturday and was found overturned in the water, early on Sunday.
President Park Geun-hye has urged rescuers to do their best.
A ferry sinking in 2014 killed over 300 people, and triggered national outrage over what was seen as an ineffective rescue operation.