Read the passage carefully and answer the questions which follow. Some words may be highlighted for you.
An American explorer has found plastic waste on the seafloor while breaking the record for the deepest ever dive. Victor Vescovo descended nearly 11km (seven miles) to the deepest place in the ocean - the Pacific Ocean's Mariana Trench. He spent four hours exploring the bottom of the trench in his submersible, built to withstand the immense pressure of the deep. He found sea creatures, but also found a plastic bag and sweet wrappers. It is the third time humans have reached the ocean's extreme depth. The first dive to the bottom of the Mariana Trench took place in 1960 by US Navy lieutenant Don Walsh and Swiss engineer Jacques Piccard in a vessel called the bathyscaphe Trieste. Movie director James Cameron then made a solo plunge half a century later in 2012 in his bright green sub.
The latest descent, which reached 10,927m (35,849ft) beneath the waves, is now the deepest by 11m - making Victor Vescovo the new record holder. As well as the Mariana Trench in the Pacific, in the last six months dives have also taken place in the Puerto Rico Trench in the Atlantic Ocean (8,376m/27,480ft down), the South Sandwich Trench in the Southern Ocean (7,433m/24,388ft) and the Java Trench in the Indian Ocean (7,192m/23,596ft). The final challenge will be to reach the bottom of the Molloy Deep in the Arctic Ocean, which is currently scheduled for August 2019. The 4.6m-long, 3.7m-high submersible - called the DSV Limiting Factor - was built by the US-based company Triton Submarines, with the aim of having a vessel that could make repeated dives to any part of the ocean.
After the Five Deeps Expedition is complete later this year, the plan is to pass the submersible onto science institutions so researchers can continue to use it. The challenges of exploring the deep ocean - even with robotic vehicles - has made the ocean trenches one of the last frontiers on the planet. Once thought to be remote, desolate areas, the deep sea teems with life. There is also growing evidence that they are carbon sinks, playing a role in regulating the Earth's chemistry and climate.