Putting Academy Award winner James Cameron underwater on our cover this month called for a little Hollywood magic. “We have to show science is exciting,” he says.

The National Geographic explorer-in-residence really was submerged—but inside a giant water tank at a soundstage he uses in Manhattan Beach, California (two 40-foot models of the Titanic, both seaworthy and wrecked versions, sat nearby).

Related video: James Cameron on taking risks.

Sand, plants, and bubbles were added to the image to create the illusion of Cameron on the seafloor, a place well-known to the director of Titanic and The Abyss.

Photographer Marco Grob (below, with camera) had just two hours to make the portrait before his subject had to leave to catch a flight for Australia.