The South Korean Coastguard said that divers had managed to get inside the ferry that sunk last Wednesday off the country's southern shore.
Sunday's operation involved 204 ships, 34 planes and 563 divers.
Ko Myung-suk, Director-General of South Korea Coastguard Equipment and Technology Bureau: "As we reported, we are at the level where we have already made it into the ferry by breaking the window. So you can see that we have definitely made progress into the ferry.
"We're unable to pinpoint where exactly the dead bodies were found. Divers themselves were also not sure about this due to the limited visibility underwater."