Washington ? In James Cameron’s fantasy films, like “Avatar” and “The Abyss,” the unexplored is splashed in color and fraught with alien danger. But on his dive to the deepest place on Earth, reality proved far different: white, barren and bland.

Yet otherworldly — and amazing.

“I felt like I literally, in the space of one day, had gone to another planet and come back,” Cameron said Monday after returning from the cold, dark place in the western Pacific Ocean, seven miles below the surface. “It was a very surreal day.”

Cameron is the first person to explore the deepest valley in the ocean since two men made a 20-minute foray there more than half a century ago. He spent about three hours gliding through the icy darkness, illuminated only by special lights on the one-man sub he helped design. That was only about half as long as planned because his battery ran low.

This deepest section of the 1,500-mile-long Mariana Trench is so untouched that at first it appeared dull. But there’s something oddly dark and compelling about the first snippets of video that Cameron shot. It’s not what you see but where it puts you. There is a sense of aloneness that Cameron conveys in the wordless video showing his sub gliding across what he calls “the very soft, almost gelatinous flat plain.”

“My feeling was one of complete isolation from all of humanity,” Cameron said.

The images “do lack the visual impact of highly colorized 3D spectacular representations of the ocean,” Bowen said. But there are still “dramatic discoveries to be made.”

The minute-long snippet, released by trip sponsor National Geographic, is just a coming attraction. Cameron will keep diving in the area, some 200 miles southwest of the island of Guam, where the depth of the trench is called Challenger Deep. And he’s already filming it in 3D for later viewing.