The chief of Indonesia's national search and rescue agency has identified the location of a ferry that sunk in a deep volcanic crater lake a week ago with some 200 people aboard.
Syaugi, who uses one name, said in a television interview on Monday that Indonesia needed international help to recover the wreckage.
A statement on Sunday from the agency had said an object that was possibly the ferry was at a depth of 490 metres.
More than 180 people are presumed drowned from the June 17 sinking of the overcrowded ferry in rough weather.
Officials said many of the dead are likely trapped inside the vessel.
Separately, police said four people including transport officials have been arrested on suspicion of negligence that led to the sinking.
Anguished relatives have criticised the search effort but Syaugi defended it, saying there had been an "all out" effort.
"We will do our best to salvage this wreck," he said. "Because we do not have robots, we are trying to find from other countries, but most of them have tools to lift a vessel from just 100 metres depth and the wreck must be cut first."
Lake Toba is a tourist attraction and the largest lake in Indonesia, extending over an area of 1145 square kilometres in the caldera of a volcano that last erupted about 74,000 years ago.
