The Smithsonian's National Zoo's four African lion cubs took a swim test Tuesday. The cubs must prove that they can swim to land and pull themselves out of the water before going on exhibit. All of the cubs passed. (Smithsonian's National Zoo)

Four of the National Zoo’s lion cubs took a dip in the water Tuesday to prove to zookeepers that they would be safe roaming around their outdoor enclosure, which features a moat.

Shera and Luke’s four cubs, born March 2, passed their swim test by keeping their heads above the water, paddling in the shallow end and climbing onto the land.

“It’s possible that a cub could be playing around and get knocked into the moat by a parent or sibling,” zookeeper Kristen Clark said. “We want to make sure that if they find themselves in that situation, they know how to pull themselves out of the water and onto shore.”

The cubs will appear in public in mid-June after receiving vaccinations, zoo officials said.

Two cubs born to Nababiep and Luke on January 24 explored a nearby yard for the first time shortly after their half-siblings’ swim test. The two will go on view beginning Friday.

The entire lion family, or pride, is expected to be on exhibit this summer.

— Christina Barron