Scientists set off this week to study the wrecks of three German submarines sunk by U.S. forces in 1942 off the coast of North Carolina during the Battle of the Atlantic.

"This expedition is the first part of a larger multi-year project to research and document a number of historically significant shipwrecks tragically lost during World War II, including U.S. and British naval vessels and merchant marine vessels," said David W. Alberg, expedition leader and superintendent of the USS Monitor National Marine Sanctuary. "The information collected during this expedition will be crucial to efforts to preserve these historic sites."

Researchers will survey and photograph visible sections of the three submarines, U-352, U-85 and U-701, using non-invasive methods. They will also study marine life found at the sites.

The wrecks, popular dive sites off the Outer Banks of North Carolina, are considered war graves and will not be disturbed during the expedition. (The word U-boat refers to German military submarines operated during World War I and World War II, and is an anglicization of the German abbreviation for "unterseeboot," or undersea boat.)

The sunken German U-boats are located in an area known as the "Graveyard of the Atlantic," which encompasses shipwrecks from both sides of the Battle of the Atlantic at recreational diving depths (less than 130 feet).

Two of the U-boats, U-352 and U-85, have been severely impacted by salvage operators and souvenir hunters since their discovery more than three decades ago. U-701 is relatively intact but also has begun to show signs of damage from illegal salvage attempts. The sub was discovered by recreational divers in 1989 before being covered by sand and rediscovered in 2004.

NOAA's Office of National Marine Sanctuaries is conducting the survey in partnership with the Minerals Management Service, National Park Service, State of North Carolina, East Carolina University and the University of North Carolina Coastal Studies Institute. The expedition runs through July 26.

Next summer, the team plans to investigate Allied wrecks in the Graveyard of the Atlantic. Some of the wrecks lie at recreational diving depths, while many are located in deeper waters where they remain untouched and in relatively good condition.