Indonesia rescued 15 survivors on its search and rescue effort on Friday (January 5) nearly one week after a ferry carrying more than 600 people sank off the coast of the country's main island of Java. Some survivors are still on life rafts in the open water, with food being airdropped to them as rough seas and bad weather prevent rescue craft from getting to them. Officials say at least 239 of those on the ferry have been rescued since it sank overnight Friday (December 29), but nearly 400 more are unaccounted for. Despite numerous reports of scores of bodies being sighted on beaches and afloat, data on the dead have lagged as searchers concentrate on getting the living to safety. Official said high waves and strong sea currents were pushing the bodies of the dead and the living eastwards in the direction of Surabaya, the capital of East Java province and Indonesia's second largest city. That means rescuers were searching along a coastline that is more than 100 miles (161 km) long, but hopes remained high for survivors. Officials said dozens of passengers had been picked up by passing ships and rescuers were also trying to reach several life rafts with people on board. Survivors speak of rough seas and dozens of people clinging onto one raft at a time. "I was in limbo for five nights on a raft. I drank sea water and rain water," one survivor, Ansori, told Reuters Television. "At the time I just thought about getting saved. Everyone was jumping into the water and I followed them. There was only enough food for one day but there were 15 of us on the raft," explained another survivor, Sugiman. According to the manifest, the Senopati Nusantara ferry was carrying 628 people, including 57 crew. Transportation Minister Hatta Rajasa has said the Japanese-built, 2,178-tonne ferry was seaworthy and had a capacity of more than 850 passengers. The ship had been heading from Kalimantan on Borneo island to Semarang. It was the second ferry disaster in the last week of 2006 after a vessel overturned on Thursday (December 28) in rough seas off Sumatra. Two people on that ferry died and 26 were missing as of late Sunday (January 31), a rescue official said. Ships and ferries are a popular means of transport among Indonesia's 17,000 islands. However, safety standards are not always enforced, and accidents occur fairly often.