Confederate submarine H.L. Hunley.JPG (copy)

A new discovery on the Hunley submarine of a roughly 1-inch gap from where the pipe should have been mounted on the side wall. If the pipe broke off the night of the Hunley’s historic mission, it may have contributed to the sinking of the submarine and the loss of her crew Monday, Jan. 14, 2019. Andrew J. Whitaker/Staff

The Confederate submarine H.L. Hunley sat buried on the sea floor for more than a century. Now a TV show is going to peel away 18 feet of ocean to show you where it was.

National Geographic Television's "Drain the Oceans" shipwreck and treasure series will feature the Charleston Civil War artifact on Monday's broadcast.

Using computer-generated imagery, the show displays "what the oceans' floors would look like if they could be seen," according to the series website.

The imagery literally drains the water away in front of viewers' eyes. In this case it means exposing the wrecked submarine on the sea bed.

Hunley underwater (copy) (copy)

The H.L. Hunley, a Confederate ship, which now sits in a chemical bath in North Charleston, was the first combat submarine to blow up a warship.

The Hunley is the hand-cranked, 40-foot-long craft that launched the world’s first successful submarine attack by sinking the Union blockade ship Housatonic off Sullivan’s Island on Feb. 17, 1864.

The Hunley and its crew of eight rammed a powder explosive into the Housatonic's hull, detonating in a massive explosion.

While the crew signaled they planned to return by reportedly flashing a blue lantern light toward shore, the sub never reappeared.

The vessel and its human remains were found and later recovered four miles offshore in 2000. The crew was buried at Magnolia Cemetery in Charleston.

Since the recovery, the sub has been undergoing conservation work at the Clemson University-run Warren Lasch Conservation Center in North Charleston on the grounds of the former Naval Base and Shipyard. The lab is open for tours on weekends.

The show's production team shot footage recently at the center.

The big mystery about the Hunley is still unresolved: Why did it sink?

Clemson University conservators working to restore the doomed vessel recently reported on a roughly 1-inch gap where the ballast tank pipe should have been mounted on the side wall of the submarine.

If the pipe broke off the night of the Hunley’s historic mission, it may have contributed to the sinking of the sub and the loss of her crew. The intake pipe was meant to fill the forward ballast tank with water.

Now mostly cleaned, the sub will sit in a conservation bath for about five years to preserve the metal and ready the vessel for permanent public display some day.

Check your local service provider for broadcast information.

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Reach Bo Petersen at @bopete on Twitter or 843-937-5744.