On the deepest dive ever made by a human inside a submarine, a Texas investor found something he could have found in the gutter of nearly any street in the world: rubbish.

Victor Vescovo, a retired naval officer, made the unsettling discovery as he descended 10,928 meters to a point in the Pacific Ocean's Mariana Trench - the deepest place on Earth - his expedition said in a statement on Monday.

BBC

His dive went 16 meters lower than the previous deepest descent in the trench in 1960.

Vescovo, the Dallas-based co-founder of private equity fund Insight Equity Holdings, found the man made material on the ocean floor and is trying to confirm that it is plastic, a spokeswoman for Vescovo's Five Deeps Expedition said.

Plastic waste has reached epidemic proportions with an estimated 100 million tonnes of it now found in the world's oceans, according to the United Nations.

Humans have reached the ocean's extreme depths for the 3d time, nearly 11km (seven miles) down the Pacific Ocean's Mariana Trench. There were sea creatures, but a plastic bag and sweet wrappers were also foundpic.twitter.com/QOqd3fVQMB — Alfons López Tena #FBPE (@alfonslopeztena) May 13, 2019

In the last three weeks, the expedition has made four dives in the Mariana Trench in his submarine 'DSV Limiting Factor', collecting biological and rock samples.

It was the third time humans have dived to the deepest point in the ocean, known as Challenger Deep.

Canadian filmmaker James Cameron was the last to visit in 2012 in his submarine, reaching a depth of 10,908 meters.

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Before Cameron's dive, the first-ever expedition to Challenger Deep was made by the US Navy in 1960, reaching a depth of 10,912 meters.

The Five Deeps Expedition

But Vescovo and his team are not stopping now, with another dive of the Horizon Deep within the Tonga Trench in the South Pacific Ocean coming up next.

The Tonga Trench was previously measured at 10,882 metres deep and is known as the second-deepest ocean trench in the world after the Marina Trench.

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Due to the small difference in measured depths between the Challenger and Horizon Deeps, Vescovo and team plan to find out once and for all if the Tonga Trench is actually deeper than the Mariana Trench.