The last visit to Challenger Deep also set a depth record at 35,787 feet.
Victor Vescovo stands next to a submarine that he took to the deepest point on planet.
"It is nearly indescribable how excited all of us are about achieving what we just did", Vescovo told the BBC.
Witnessing the dive from the Pacific was Don Walsh.
Vescovo broke the previous Mariana Trench diving record by about 36 feet.
In the Java Trench, the deepest point of the Indian Ocean, researchers identified a gelatinous animal - thought to be a stalked ascidean, otherwise known as a sea squirt - which they said does not resemble anything seen before.
During their descent, the expedition crew saw a number of sea creatures - a spoon worm at 7000 metres and a pink snailfish at 8000m - and believe they discovered four new species of crustaceans called amphipods, similar to prawns.
Discoveries in the Challenge Deep included "vibrantly colorful" rocky outcrops that could be chemical deposits, prawn-like supergiant amphopods, and bottom-dwelling Holothurians, or sea cucumbers.
But he also saw evidence of plastic pollution - something that other expeditions have seen before.
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.
Scientists plan on testing the creatures collected on the expedition to see if they contain microplastics.
Mr Vescovo's latest dive is part of the "Five Deeps expedition", where he is attempting to explore the deepest parts of all five oceans.
It has been funded by Mr Vescovo, a private equity investor, who before turning his attention to the ocean's extreme depths also climbed the highest peaks on the planet's seven continents.
It was the voyage to break the record for the world's deepest ocean dive.
"Honestly, towards 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", he recalls.
In the last three weeks, the expedition has made four dives in the Mariana Trench in Mr Vescovo's submarine, DSV Limiting Factor, collecting biological and rock samples. According to the BBC, the pressure at the bottom of the ocean is equal to about 50 jumbo jets piled on top of a person.
As well as working under pressure, the sub has to operate in the pitch black and near freezing temperatures.
His voyage, in a submersible named The Limiting Factor, is part of a landmark odyssey into the world's watery depths that's being filmed for Discovery Channel - dubbed the Five Deeps Expedition.
Anthony Geffen, creative director of Atlantic Productions, said it was the most complicated filming he'd ever been involved with.
3 die when sightseeing planes collide in Alaska
The Coast Guard said it had launched a helicopter crew and two boat crews from its Ketchikan station to search for the missing. All patients were in fair or good condition, according to Marty West, a spokeswoman for PeaceHealth Ketchikan Medical Center.