Plastic Pollution: American diver Victor Vescovo finds plastic bag at bottom of Mariana Trench

An American undersea explorer who has completed what is claimed to be the deepest manned sea dive ever recorded, found a plastic bag and candy wrappers in the southern end of the Pacific Ocean's Mariana Trench.

Victor Vescovo journeyed 35,853 feet to the bottom of the Challenger Deep as part of a mission to chart the world's deepest underwater places, CNN reported.

Making multiple trips nearly 11 km to the ocean floor -- one of them four hours in duration -- Vescovo set a record for the deepest solo dive in history, his team said.

The previous record was held by "Titanic" director James Cameron in 2012.

The ocean depths represent some of the least explored and remote places on the planet. The Mariana Trench is deeper than Mount Everest is tall.

Vescovo, a 53-year-old financier with a naval background, told CNN that his journey to the depths was about testing the limits of human endeavour as much as scientific discovery.

As well as four new species that could offer clues about the origins of life on Earth, Vescovo observed the plastic bag and candy wrappers at the deepest point on the planet.

Details of the voyage, made on May 1, were released for the first time on Monday.

A key mission objective was to capture video evidence of what was at the bottom of the Challenger Deep, which was first explored in 1960.

"I criss-crossed all over the bottom looking for different wildlife, potentially unique geological formations or rocks, man-made objects, and yes, trying to see if there was an even deeper location than where the Trieste went all the way back in 1960," Vescovo said.

Discoveries in the Challenge Deep included "vibrantly colourful" rocky outcrops that could be chemical deposits, prawn-like supergiant amphipods, and bottom-dwelling Holothurians, or sea cucumbers.

The team of the Five Deeps Expedition that Vescovo's voyage was a part of, said its scientists were going to perform tests on the creatures found to determine the percentage of plastics found in them.