Leonardo DiCaprio Goes Snorkeling with Girlfriend Camila Morrone

Leonardo DiCaprio wanted to make sure he could see clearly underwater while vacationing in Italy with his Argentinian girlfriend -- and by the looks of her ... we understand why.

Leo and his model boo, Camila Morrone, were snorkeling in Nerano, where the couple threw on their flippers and goggles for a peek under the deep blue.

It's kinda funny ... LDC stayed rockin' his full snorkel getup for a solid minute aboard the boat they were on, while Camila opted for an au naturel look, front and back. Seeing how she was nearby for the nosedive ... ya can't blame him for wanting a clear view.