HAIFA, Israel (AP) _ A U.S. nuclear submarine is combing the depths of the Mediterranean, searching for an Israeli submarine missing since 1968.

``We are going to do everything we can to find it,'' said Doug Perry of Richford, Vt., chief navigator of the NR-1, which docked Sunday at the Israeli port of Haifa after completing a third of its six-week mission.

Israel long has searched for the Dakar, which disappeared off Crete on its way home from Britain with 69 crew members aboard. All that has been found of the submarine was a buoy that turned up along the Egyptian coast in 1969.

Mayer Nir, the Israeli navy's personnel chief, said it probably sank because of rough waters, design problems and human error; he ruled out the possibility of an attack.

Lt. Col. Yehuda Weinraub, an Israeli army spokesman, said Israel has never lost hope of finding the craft, because ``it is our duty to bring fallen soldiers to rest in Israel.''

The NR-1 has long-term submerging capability, 17 underwater cameras and sensitive probing equipment that is hoped to make this search successful.

Because of its nuclear core, the 150-foot vessel has a virtually unlimited power source that allows for lengthy searches of the sea floor. Its advanced sonar can locate a piece of metal the size of a soda can 1,000 yards down.

Its 11 crew members are submerged for 30 days at a time in quarters so small that one sailor sleeps under a chair. Special candles of barium chloride are used to give off oxygen, helping the crew breathe.

Still, joked Lt. Cmdr. Charles Richard, from Decatur, Ala., ``if they figured out a way to grow food down here, we would never come up.''

Richard said the mission _ which also includes aiding excavations of Roman shipwrecks _ is useful training.

The NR-1 is to return to port at Groton, Conn. by summer's end.