The team also reportedly found a plastic bag and several candy wrappers.
Titanic director James Cameron repeated the feat in 2012. The expedition reached a maximum depth of 10,928 meters (35,853 feet deep) 16 meters/52 feet deeper than any previous manned dive. The 15-foot-long, 12-foot-high submersible features a 3.5-inch-thick titanium pressure hull that can accommodate two people, and dives can be conducted solo or as a pair.
"It is nearly indescribable how excited all of us are about achieving what we just did", Vescovo said.
Vescovo also made progress toward his larger goal.
Among the observations from the dive: A plastic bag and sweet wrappers seen at Earth's deepest spot, four new species (pending scientific analysis), red and yellow rocky outcroppings, and the deepest living fish-the Mariana snailfish seen at 26,247 feet.
Mr Vescovo also saw angular metal or plastic objects, one with writing on it. It's something that other expeditions using landers have seen before.
According to reports, more than eight million tons of plastic is dumped into our oceans every year.
From behind the glass of a submersible created to withstand extreme pressures, he spent hours observing and documenting the quiet, dark alien world.
Prior to Cameron's dive, the first-ever expedition to Challenger Deep was made by the U.S. Navy in 1960, reaching a depth of 10,912 meters.
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.
It can withstand the crushing pressure found at the bottom of the ocean: 1,000 bars, which is the equivalent of 50 jumbo jets piled on top of a person.
"Most importantly we have opened the door to the final frontier-the exploration of the hadal zone and the workings of the deepest parts of the world's oceans", said Rob McCallum of EYOS Expeditions, whose company is managing the expedition.
At the very bottom, he found colorful rocky structures, weird critters and the ever-pervasive mark of humankind - plastic.
Vescovo found undiscovered species as he visited places no human had gone before.
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