Although you would not have thought so a couple of years ago, the Titanic isn't the only piece of history that lies beneath the water.
As a matter of fact, there is an entire group within the National Park Service, diving archeologists, artists and rangers, whose job it is to promote preservation of historic shipwrecks and other underwater archeological sites. It's called the Submerged Cultural Resources Unit.
Among the sunken pieces of history that have drawn the unit's attention is the USS Arizona, one of the battleships that went to the bottom when the Japanese attacked Pearl Harbor on Dec. 7, 1941. A memorial was dedicated over the sunken hull in 1962 and became a National Park Service area in 1980.
Daniel Lenihan, who has been diving as a park ranger and archeologist for the National Park Service since 1972, served as the unit's first chief, appointed in 1980. In addition to other writings, he has incorporated his knowledge into a novel, Wake of the Perdido Star, which he wrote with actor Gene Hackman.
The two men are a subject of a profile this weekend by Correspondent Martha Teichner on CBS News Sunday Morning.
To see Lenihan's article about revisiting the Arizona underwater, click here.