Submarines aren't unusual today, just about every military in the world operates them as do a number of private companies in the ocean exploration realm. During the civil war 150 years ago a sub was put into service by the Confederate army in its attempt to win the civil war.
The sub is called the H.L. Hunley and its remains are currently being cleaned so that scientists can study them to determine what led to the sub sinking. Scientists are removing debris and rust from the hull of the sub, which was the first sub to sink an enemy ship in history.
The sub was powered by a hand cranked drive system and by removing the debris from the hull; it will be visible for the first time in 150 years. The sub sunk a Union blockade ship called the USS Housatonic in 1864. Damage to the hull is believed to be the reason why the sub sank. When the sub was found in 1995, the remains of the crew were still inside.