Vescovo's team believes they have found four new prawn-like species at the bottom of the Mariana Trench.
Victor Vescovo descended almost 11km (seven miles) to the deepest place in the ocean - the Pacific Ocean's Mariana Trench. The previous record was held by "Titanic" director James Cameron in 2012.
Vescovo, a 53-year-old financier with a naval background, tells CNN Travel his journey to the depths was about testing the limits of human endeavor as much as scientific discovery.
Plastic waste has reached epidemic proportions in the world's oceans with an estimated 100 million tonnes dumped there to date, according to the United Nations.
A robotic lander photographs the creatures in the deep Mariana Trench and the submersible in the background.
The team said its scientists were going to perform tests on the creatures found to determine the percentage of plastics found in them.
Next up is a trip to the bottom of the as-yet unexplored Molloy Deep in the Arctic Ocean, due to be completed in August 2019.
He spent four hours exploring the bottom of the trench in his submersible, built to withstand the vast pressure of the deep.
Photos showing Victor Vescovo, his launch in Triton submersible, the bottom of Mariana Trench, and Vescovo being congratulated by Don Walsh courtesy of the Deep Five Expeditions and Discovery Channel.
As well as the Mariana Trench in the Pacific, in the last six months dives have also taken place in the Puerto Rico Trench in the Atlantic Ocean (8,376m), the South Sandwich Trench in the Southern Ocean (7,433m) and the Java Trench in Indian Ocean (7,192m). Humanity's impact had reached the deepest parts of the sea floor, too, the team realized.
The Mariana Trench is a deep and long hole in the Pacific Ocean floor between Japan and Australia.
At the deepest point, they were accompanied by some transparent bottom-dwelling sea cucumbers (Holothurians) and an amphipod called the Hirondellia gigas.
In the last three weeks, the expedition has made four dives in the Mariana Trench in Vescovo's submarine, DSV Limiting Factor, collecting biological and rock samples.
Victor Vescovo, a private equity investor, climbed the highest peaks on the planet's seven continents before turning his attention to the ocean's extreme depths.
In the recent dive, Walsh accompanied a team up above on the ship, as Vescovo descended alone in a submersible called the DSV Limiting Factor.
Deep sea dives have proven that areas thought to be remote and desolate are actually filled with life - and apparently, pollution. There is also growing evidence that they are carbon sinks, playing a role in regulating the Earth's chemistry and climate.
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