The site is in Wassaw Sound where the bomb was purportedly lost.

1958 Tybee Island mid-air collision

The Tybee Island B-47 crash was an incident on February 5, 1958, in which the United States Air Force lost a 7,600-pound (3,400 kg) Mark 15 hydrogen bomb in the waters off Tybee Island near Savannah, Georgia, USA. During a practice exercise the B-47 bomber carrying it collided in midair with an F-86 fighter plane. To protect the aircrew from a possible detonation in the event of a crash, the bomb was jettisoned. Following several unsuccessful searches, the bomb was presumed lost somewhere in Wassaw Sound off the shores of Tybee Island.

• http://en.wikipedia.org/wiki/1958 Tybee Island mid-air collision