Vanessa O'Brien inside her submersible 

(C) Enrique Alvarez 2020 (Vanessa O’Brien); Jim McMahon/Mapman® (globe); Oceangate Expeditions (Titanic); COURTESY OCEANLAB, UNIVERSITY OF ABERDEEN (Snailfish); © Triton Submarines (sub); Shutterstock.com (all other images)

Journey Into the Deep

An underwater explorer travels to the ocean's deepest point.

As You Read: Identify three reasons most life can’t survive in the deepest ocean. 

In June 2020, Vanessa O’Brien squeezed into a submersible. That’s a vehicle that travels underwater. She was about to start a risky ocean adventure.

Eight years earlier, O’Brien had climbed Mount Everest. That’s the world’s highest point. 

Now she was trying to reach Earth’s lowest point. Challenger Deep is the deepest part of a long, narrow canyon called the Mariana Trench. It’s nearly 7 miles below the surface of the Pacific Ocean.

In June 2020, Vanessa O’Brien squeezed into a submersible. That’s a vehicle that travels underwater. She was about to start a risky ocean adventure.

Eight years earlier, O’Brien had climbed Mount Everest. That’s the world’s highest point.

Now she was trying to reach Earth’s lowest point. Challenger Deep is the deepest part of a long, canyon called the Mariana Trench. It’s nearly 7 miles below the surface of the Pacific Ocean.

An Adventure Begins

O’Brien’s submersible was lowered into the water by a crane from a ship. Then she descended. The water got darker and colder. After about four hours, she reached the deepest place on Earth.

“The bottom looks like what I imagine the moon to look like,” says O’Brien. 

O’Brien’s submersible was lowered into the water by a crane from a ship. Then she descended. The water got darker and colder. About four hours passed. Then, she reached the deepest place on Earth. 

“The bottom looks like what I imagine the moon to look like,” says O’Brien.

A Dangerous Trip

Jim McMahon/Mapman®

The ocean covers about two-thirds of Earth’s surface. But humans have yet to explore most of it. 

The biggest danger to ocean explorers is water pressure. That’s the force of water pressing on their bodies as they go deeper into the ocean. When very deep, the pressure can crush people and subs.

That’s why O’Brien’s sub was built using one of the strongest metals on Earth. Still, if something were to go wrong, it would take the sub hours to reach the surface and get help. 

The ocean covers about two-thirds of Earth’s surface. But humans have yet to explore most of it. 

The biggest danger to ocean explorers is water pressure. That’s the force of water pressing on their bodies as they go deeper into the ocean. When very deep, the pressure can crush people and subs.

That’s why O’Brien’s sub was built using one of the strongest metals on Earth. Still, if something were to go wrong, it would take the sub hours to reach the surface. It would also take a while get help.

Exploring the Floor

The Mariana Trench is about five times longer than the Grand Canyon. During the expedition, O’Brien helped map a mile of the trench. She also collected water samples and took videos.

The pressure, darkness, and cold temperature make it difficult for most sea creatures to survive here. But there is some life. The sub’s cameras showed tiny creatures called bristle worms along the sandy trench floor. 

O’Brien’s ocean mission was a success. She became one of only two people to reach Earth’s highest and lowest points. But O’Brien says you don’t need to go far to be an explorer. 

“All kids have to do is tap into their curiosity and go and explore with an open mind,” she explains. 

The Mariana Trench is about five times longer than the Grand Canyon. During the expedition, O’Brien helped map a mile of the trench. She also collected water samples. And she took videos.

It's hard for most sea creatures to survive here. That's because of the pressure, darkness, and cold temperature. But there is some life. The sub’s cameras showed tiny creatures on the sandy trench floor. They're called bristle worms.

O’Brien’s ocean mission was a success. She became one of only two people to reach Earth’s highest and lowest points. But O’Brien says you don’t need to go far. Anyone can be an explorer.

“All kids have to do is tap into their curiosity and go and explore with an open mind,” she explains.

  1. Based on the text and pictures, what is a submersible? What do you know about the submersible Vanessa O’Brien used?
  2. What did O’Brien do during her expedition to the Mariana Trench?
  3. What can you learn from the “Layers of the Ocean” diagram?
  1. Based on the text and pictures, what is a submersible? What do you know about the submersible Vanessa O’Brien used?
  2. What did O’Brien do during her expedition to the Mariana Trench?
  3. What can you learn from the “Layers of the Ocean” diagram?
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