There are few things more unsettling at sea than watching the horizon suddenly disappear behind a wall of water.

Nathan and Lindsey, the couple behind popular boating channel The 71 Percent , experienced exactly that during their ambitious Pacific crossing. In dramatic footage from the voyage, their motor yacht encounters a wave they estimated at roughly 20 feet, violently knocking the vessel onto its side before it rights itself.

“Motor Yacht Knocked Flat by 20ft Wave,” the couple titled the episode, describing the encounter as a “Pacific Crossing Nightmare.” Their website now describes it similarly: “20ft Wave Nearly Rolled Our Motor Yacht.” Check out the scary scenes below:

The two are no strangers to adventure. Nathan and Lindsey left demanding careers—including work in motorsports—to become liveaboard cruisers documenting their travels.…