Barry Clifford is just like Indiana Jones. Only he wears a baseball cap with “Whydah Dive Ops” on it. And doesn’t carry a whip. And he scuba dives.

Clifford is the underwater explorer who discovered the sunken Whydah, a slave ship turned pirate vessel that’s the focus of “Real Pirates” at the National Geographic Museum.

When Clifford and his crew found the treasure-laden wreck in 1984, “we didn’t know what we had,” he says. “Well, I did, but no one believed me.”

It wasn’t until they removed the concretion (the crust that forms around stuff left in seawater for a few hundred years) on the ship’s bell that Clifford had proof. “A team member was chipping away, and we saw a ‘W.’  He chipped away a little more, and there it was: ‘Whydah.’ ”

Finding the wreck was a childhood dream come true. Growing up in Cape Cod, Mass., Clifford heard the legend of the ship’s captain, Sam Bellamy, who was making his way back to his beloved, Maria Hallett, when the Whydah went down in April of 1717.

“There was this meadow, called Goody Hallett’s meadow,” Clifford says. “We all believed she still ran around.” Catching her ghost didn’t interest Clifford, but finding Bellamy’s ship did.

“Real Pirates” covers Clifford’s discovery of the Whydah as well as the ship’s nefarious past. Slave ships were popular pirate targets; since traders wanted captives to survive their journeys, the vessels were built for speed.

In early 1717, Bellamy and his men took the Whydah, added it to Bellamy’s fleet and continued their spree as the 18th-century version of car thieves: Grab a ship, strip it of its valuables and move on.

Some of those valuables — plus weaponry, personal effects and other goodies — are on view in “Real Pirates.” “We’ve got 15,000 to 20,000 coins here,” says Clifford. “Legally, you can’t sell it, so it’s really impossible to tell, but I’m sure it’s worth several million dollars.”

The Whydah hasn’t given everything up yet. “There could be 100,000 coins total,” says Clifford. “And we think we know where they are.”

Which means Indiana Jones will be wiggling back into his wetsuit soon enough.

National Geographic Museum, 1145 17th St. NW; through Sept. 2, $7-$11; 202-857-7588. (Farragut North)