Details of his trip were released on Monday.
His double record-setting dive was part of a mission to explore the uncharted depths of the world's oceans, collect scientific samples, and look for new species.
It wasn't all grim findings, Vescovo also discovered at least three new species of marine life, including a shrimp with extra long legs, and collected rocks from an area where humans have never been.
Most of the plastic found at the bottom of the sea by divers (89%) has one thing in common, the Deep Sea Debris Database reported: it's waste such as plastic bottles and bags, created to be used just once, then thrown away. It's not the first time plastic has been found at the bottom of the sea, but it's a reminder of the scale of the problem. While he saw particles of an object, he can't be certain if it was made of plastic or metal. "But we ignore it at our peril".
"Our goal was to build a submersible capable of repeated dives to any depth with its pedigree and security assured by third-party accreditation", said Patrick Lahey, President of Triton Submarines.
"There were some small, translucent animals", gently moving about, Vescovo said. After Vescovo's record-breaking dive, other team members took four other subsequent dives to the trench.
Among the discoveries made aboard the The Limiting Factor - the world's first titanium-hulled, two-person submersible to dive this far - were giant prawn-like amphipods and bottom-feeding sea cucumbers.
Rob McCallum from EYOS Expeditions, the company managing the expedition, described the achievement as a "monumental week for ocean exploration".
The Five Deeps Expedition is being filmed for a five-part Discovery Channel documentary series due to air in late 2019.
"It feels like a great privilege that I was able to do this as a human being", he said.
"You know, there's so much we don't know", Cameron added.
"Honestly, toward the end, I simply turned the thrusters off, leaned back in the cockpit and enjoyed a tuna fish sandwich while I very slowly drifted just above the bottom of the deepest place on Earth, enjoying the view and appreciating what the team had done technically", Vescovo said.