An American diver broke the record for deepest submarine dive ever and found something disheartening at the bottom of the ocean - a plastic bag.
His dive went 16 meters lower than the previous deepest descent in the trench in 1960. The previous record was held by "Titanic" director James Cameron in 2012.
In total, Mr Vescovo and his team made five dives to the bottom of the trench during the expedition. Robotic landers were also deployed to explore the remote terrain.
"It is nearly indescribable how excited all of us are about achieving what we just did", Vescovo told BBC News. "This submarine and its mother ship. took marine technology to a ridiculously higher new level by diving-rapidly and repeatedly-into the deepest, harshest, area of the ocean".
A type of long-appendaged amphipod was discovered at the bottom of the Challenger Deep, in the Mariana Trench.
This is a widespread problem for sea creatures, even those living extremely deep in the ocean, a recent study has found.
"Now in the winter of my life, it was a great honour to be invited on this expedition to a place of my youth".
Humanity's impact on the planet was also evident with the discovery of plastic pollution. "I feel so fortunate to have had the means, been able to assemble such a great technical team, and work with others on the expedition to make it all a reality".
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.
Victor Vescovo spent four hours exploring the bottom of the trench.
The team said its scientists were going to perform tests on the creatures found to determine the percentage of plastics found in them. They found one 8,530 feet (2,600 m) below the surface, one 14,600 feet (4,450 m) and two at the deepest point they reached.
Spending four hours scouring the sea floor, Vescovo also took time to enjoy the moment.
The team next plans to conduct dives in the Tonga Trench in the South Pacific Ocean.
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 by oceanographers Don Walsh and Jacques Piccard in submersible called Bathyscaphe Trieste.
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.
As well as working under pressure, the sub has to operate in the pitch black and near freezing temperatures. Vescovo, a private equity investor, is funding the expeditions. Atlantic Productions for Discovery Channel/Handout via REUTERS. The group is using a submersible called Limiting Factor to complete its challenge.