The Navy has a secret indoor ocean that holds over 12 million gallons of water

This is one ocean you might not want to swim in.

The Navy owns one of the largest indoor oceans in the world. The maneuvering and seakeeping basin is nicknamed the MASK. Built in 1962 and renovated in 2013, it’s located at the Naval Surface Warfare Center in Carderock, Md.

The 360-foot-long and 240-foot wide body of water has depths ranging from 20 to 35 feet. There are 216 individually controlled electromechanical wave boards lined around the pool’s edge to recreate various oceanic conditions.

“There are many different kinds of waves,” Calvin Krishen, NSWC engineer, says in a YouTube video uploaded by the Department of Defense. “Waves are different in different parts of the world and they are different depending if you are close to shore, or away from shore or whether you’re in a storm or not. We actually have the capability of programming all those different types of waves to test.”

Operability, ship motions and efficiency are some of the things the engineers assess. This allows MASK researchers to determine a new vessel’s strengths and weaknesses to ensure it meets expected performance goals. The testing process also ensures ships have the correct configuration and it helps to establish operational guidelines for the crew.

“Though this seems a little disconnected from the warfighter,” said NSWC engineer Dr. Christopher Kent. “This is an integral part of making a fully functional ship that gets us to the theaters and to the places that we need to be in this world to keep the American public safe.”

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