'Expedition Unknown' Explorer Josh Gates Discovers Secret Tunnel in Exclusive Clip

Explorer Josh Gates is back and determined to get to the bottom of a tantalizing historical [...]

Explorer Josh Gates is back and determined to get to the bottom of a tantalizing historical adventure in the upcoming season of Expedition Unknown, returning to Discovery Wednesday, Aug. 7 at 9 p.m. ET. In a PopCulture.com exclusive sneak peek of the new season, Gates and his partner discover a promising man-made tunnel on their hunt for new Dead Sea Scrolls during their mission into the Middle East.

Shimmying their way down into the "claustrophobic" tunnel, Gates hypothesizes the passage could lead to just what they're looking for.

"The narrow tunnel leads upwards from the ritual bath," he explains. "This is exactly the kind of hiding place we've been look for. A prime spot to secret away scrolls."

Penetrating the rock with a drill, Gates breaks out a miniature camera affixed to a flexible cable in order to see what lays on the other side.

"Oh my God, it keeps going," he exclaims excitedly. "There's a tunnel."

Curious fans will have to tune in to see the conclusion of Gates' tunnel finding, as well as a mission into the remote mountains of Siberia in the dead of winter investigating one of the "coldest cases of the Cold War" -- the deaths of nine hikers on Russia's Dead Mountain. In addition, Gates will search for Sir Frances Drake's lost fortune in the depth of Panama, as well as the infamous cryptid, the Chupacabra, in Puerto Rico.

And while there's plenty of mysteries to be investigated on land, Gates is also diving into shark-infested waters to unravel the mystery of the mighty Megalodon to kick off Shark Week 2019 on July 28. Will he discover the secret to the massive shark's extinction — or hiding?

Expedition Unknown returns to Discovery for an all-new season Wednesday, Aug. 7 at 9 p.m. ET/PT. And don't miss Expedition Unknown: Megalodon, kicking off Shark Week 2019 Sunday, July 28 at 8 p.m. ET/PT on Discovery.

Photo credit: Discovery