Indonesia’s military and family members paid their last respects to the 53 submarine crew members who died when their vessel sank and broke apart in the depths off the resort island of Bali.

The ceremony included relatives casting flowers into the ocean from the navy’s hospital ship.

Indonesia is planning to recover the KRI Nanggala 402 with the help of a Chinese navy ship that is capable of lifting objects 1,000 metres (3,280 feet) deep.

The navy said the submarine sank April 21 to a depth of 600-700 metres (2,000-2,300 feet), much deeper than its collapse depth of 200 metres (655 feet), at which point water pressure would be greater than the hull could withstand.

President Joko Widodo met the families of the 53 crew members and expressed his condolences.

The German-built diesel-powered submarine had been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the defence ministry said.

Indonesia, the world’s largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.