James Cameron, the filmmaker whose credits include “Avatar” and “Titanic,” plunged on Sunday in a minisubmarine of his own design to the bottom of the planet’s deepest recess, sinking through the dark waters of the western Pacific to a depth of nearly seven miles.

The National Geographic Society, which is helping sponsor the expedition, the first in 52 years to descend so deep, said he reached the bottom at 2:52 p.m. Pacific Daylight Time.

Cameron returned to the surface Sunday evening, according to Stephanie Montgomery of the National Geographic Society, The Associated Press reported. His return was a “faster-than-expected 70-minute ascent,” according to National Geographic.

After seven years of planning — done with a team in Australia and largely in secret — Cameron strode up to his sleek 24-foot-long craft, folded his frame into a steel personal capsule just 43 inches wide and plummeted through miles of icy darkness into a trough known as the Challenger Deep. Rough seas had delayed his dive about two weeks.

“Just arrived at the ocean’s deepest pt,” Cameron said in a Twitter message earlier on Sunday. “Hitting bottom never felt so good. Can’t wait to share what I’m seeing w/ you.”

Cameron’s vehicle is unique among submersibles, its vertical axis meant to speed its descent and maximize time on the bottom. His goal is to explore the dark seabed for six hours, taking pictures and extracting samples of the fauna, before returning to sunny realms.