SIMALUNGUN (Indonesia) • Indonesian authorities yesterday turned to cutting-edge sonar technology as they searched one of the world's deepest lakes for victims of a deadly ferry disaster.
Search teams hope the equipment, on loan from Indonesia's navy, will help find the overloaded boat which sank on Monday in Lake Toba, a picturesque tourist destination in Sumatra.
Just three passengers have been confirmed dead so far, while 18 were rescued.
But official estimates list 193 others - including children - as missing, which has raised fears that many bodies are trapped inside the ferry at the bottom of the lake.
The accident could be one of Indonesia's deadliest water transport disasters.
Despite a massive search operation involving some 400 personnel, the vessel has still not been located after four days.
Lake Toba, which fills the crater of a super-volcano that exploded in a massive eruption tens of thousands of years ago, is 500m deep in parts, hampering the search effort. It covers 1,145 sq km.
Sonar technology uses sound pulses to detect and pinpoint underwater objects. The advanced equipment rolled out for the search effort is powerful enough to work at the lake floor, the authorities said.
"Our search target for the ship is at a depth of 500m," Mr Budiawan, an official at Indonesia's search-and-rescue agency, said.
"(This equipment) can reach 600m."
A lack of progress in the hunt for victims has sparked anger among some of the hundreds of people keeping vigil by the shore as they wait for news about missing loved ones.
The traditional wooden boat could have been carrying five times the number of passengers it was built to hold, along with dozens of motorcycles, officials have said.
The vessel is believed to have been operating illegally with no manifest or passenger tickets and the authorities have struggled to pinpoint the exact number on board when it went down in bad weather.
They have relied on reports from survivors and the families of missing relatives who may have been on the doomed vessel.
Mr Tua Sagala, the captain and owner of the boat, along with two crew members, is being questioned by police.
Survivors said the boat began shaking as it struggled to navigate strong winds and high waves about halfway into the 40-minute trip from an island in the middle of the lake to shore.
Despite the search efforts, families and relatives are losing patience. "There have been four days of searching, but no more victims have been found, including 12 members of my family," said 40-year-old Jadianto Nainggolan.
Traditional vessels such as the one in the Lake Toba disaster are often packed beyond capacity and lack safety equipment. Nearly 80 people died in a ferry accident on Lake Toba in 1997.
AGENCE FRANCE-PRESSE, THE JAKARTA POST/ASIA NEWS NETWORK