Investigators are launching a new effort next month to retrieve the "black box" of a freighter that sank last October with 33 crew members on board.

The National Transportation Safety Board on Monday said NTSB, U.S. Coast Guard and Navy personnel will depart in early July for the site near the Bahamas where the El Faro sank. They'll be accompanied by engineers from a private company that specializes in underwater projects.

The ship's voyage data recorder couldn't be retrieved when it was located in April because of obstructions that require specialized equipment.

The 790-foot freighter sank in 15,000 feet of water after losing propulsion between Jacksonville, Florida, and Puerto Rico, during Hurricane Joaquin. All 33 crewmembers died.

The recorder may hold audio from the ship's bridge that can shed light on its final moments.