It is the deepest ocean trench discovered on the planet 35,876 feet, or about 7 miles. It’s called the Mariana Trench, and it’s located in a remote part of the Pacific Ocean, southwest of Guam.
Several submarine divers have descended to the bottom, but due to lack of oxygen and deep-sea pressure, they have only explored for short periods of time.
“The length of time a human being can stay in such a confined space without food, water or oxygen is still really limited,” said Dwight Coleman, a deep-sea oceanographer and expedition leader at the University of Rhode Island.
It is a great big ocean and for many explorers it is also the last remaining unknown frontier. Oceans cover about 70 percent of the Earth’s surface, so it should come as no surprise that when it comes to exploration, we’ve barely scratched the surface. Until now, human eyes have only seen about 5 percent of the ocean floor.
Yet, in the time we were there, we discovered a world of our own, surviving miles below humanity.
The ocean depth
The deepest parts of the ocean are somewhat creepy places. They are home to a peculiar set of species that have adapted to life in an unforgiving ecosystem. By comparison, the trench is almost 10,000 feet deeper than Mount Everest is tall. And surviving deep isn’t easy, but this dusty dark world still supports an abundance of single-celled creatures that look like amoebas, as well as small floating crustaceans. The newly discovered hadal snail described in a 2017 journal article ZooTaxais pink, scaleless and at the top of the Mariana Trench food chain.
A 2019 expedition to the Philippine Trench, with Philippine oceanographer Deo Florence Onda and American explorer Victor Vescovo, explored Emden Deep, known as the third deepest part of the ocean. Unfortunately, this successful mission to the “bowel of the deep” revealed a dirty little surprise: trash.
“Veskovo was surprised to see two black eyes staring back at him, only to realize they belonged to a teddy bear,” according to the press release exemption marking the event.
But mostly, these trenches are deep pockets of mud, and compared to other parts of the ocean floor, Coleman says, they don’t contain the necessary resources to attract so many deep-sea explorers.
There were a few though. The first to dive to the Mariana Trench was Jacques Picard in 1960which used a US Navy submarine to make the five-hour journey to the depths, where it hung for about 20 minutes.
In 2012, the famous director James Cameron ventured into the deepest part of the Mariana Trench, known such as Challenger Deep, in a self-designed submarine. He spent about three hours taking pictures and videos to share with the world. But when it comes to real research, we’re not there yet.
“Much more effort is being put into exploring parts of the ocean floor where there are underwater volcanoes, hydrothermal vent systems, oil or mineral resources that are not at these depths,” says Coleman.
Mapping the seabed
Coleman’s team uses shipboard sonar to make high-resolution maps and identify areas for further exploration using remotely operated vehicles (ROVs). These ROVs can collect samples from the ocean floor to examine in a laboratory and take photos and video of the ocean floor.
But it’s not just the ecosystem that fascinates Coleman, he’s also intrigued by the study of what man leaves behind. He has spent years studying ancient shipwrecks at the bottom of the Black Sea, a seabed known to be anoxic, meaning it lacks oxygen and life beyond a certain depth. This deep salt layer is separated from the layers closer to the surface, which receive oxygen from the atmosphere.
“Here we were looking at preserving human history, not animal life,” he says.
And since we’ve only discovered a snapshot of what’s deep in the ocean, Coleman and his team hope to help change that. “The goal is to map the entire ocean floor by 2030,” he says.