Wreck divers have forever claimed finders/keepers
when it comes to retrieving artifacts from sunken ships.
However, federal and state governments are more frequently
claiming the artifacts, saying that they belong
in the public domain and divers who find them don’t
own them.
In 1935, during fog, the anchored 630-ton
  Lightship Nantucket LV-117 was sideswiped by the
  Olympic, a British ocean liner and Titanic’s sister ship.
  The lightship sank in minutes, taking four crew members
  with her. For 64 years, the LV-117 lay hidden in
  200 feet of water 50 miles south of Nantucket Island,
  Mass., until an exploration team plundered the ship
  and desecrated a gravesite.  
Eric Takakjian of Fairhaven, Mass., a former Coast
  Guardsman and avid wreck diver, spent years researching
  the ship, eventually using side-scan sonar to find it.
  On July 18, 1998, Takakjian and a team of divers made
  their first dive on the ship, and during a dozen more
  dives he removed the ship’s binnacle, 1,200-pound
  signal bell, the helm, portholes, telegraph, and signal
  light. Then he presented lectures, pictures and artifacts
  at diving symposiums and shows throughout New
  England.  
Nearly a year after he found the ship and began
  removing artifacts, Takakjian applied to the Coast
  Guard to explore it. But, they irrevocably denied him
  permission, unaware of Takajian’s plunderings.  
In 2004, members of the U.S. Coast Guard
  Lightship Sailors Association, dedicated to the preservation
  of lightship history, learned of Takakjian and
  his artifacts and notified the Coast Guard. Larry R.
  Ryan, president of the Association, said “A grave ship
  should be treated the same as any other grave, six feet
  deep or 200 feet deep, it makes no difference. We
  were appalled by the divers’ actions. I think only a true
  sailor can appreciate this.”  
Coast Guard special agent Michael R. Burnett collected
  evidence, conducted interviews, and located
  the stolen artifacts. The U.S. Department of Justice
  and Coast Guard sued to recover them last March.
  While Takakjian and his colleagues admitted to their
  plundering, their lawyer claimed they had the right
  to retain the property. Then the Justice Department
  threatened criminal prosecution. Their mood quickly
  changed. They relinquished their claims on the recovered
  property, and promised to never dive again on the
  Nantucket. The artifacts will soon be on public display.  
Burnett says it’s important for Coast Guard history
  to preserve the ship’s legacy and to protect the
  final resting place of those who died in the service of
  their country. “People should not exploit wrecks for
  personal gain, profit and notoriety. They should face
  penalties, whether civil or criminal.”