Today’s Wonder of the Day was inspired by Hannah. Hannah Wonders, “What is in the deepest part of the ocean?” Thanks for WONDERing with us, Hannah!

Wonders have taken us to the highest peak on Earth. They’ve taken us high into the atmosphere. They’ve even gone to outer space! But today’s Wonder of the Day will take us in the opposite direction. That’s right! Today, we’re learning about the deepest place on Earth.

Where is the deepest place on Earth? It’s beneath the surface of the Pacific Ocean to the southeast of Japan. There, you’ll find a deep, crescent-shaped trench. This is called the “Mariana Trench.” Near the southern tip of the crescent, there is a small slot-shaped area. This is the deepest point on Earth—Challenger Deep.

The bottom of Challenger Deep is about 36,000 feet below sea level. That’s nearly seven miles! This makes it the deepest known place on Earth. Imagine placing Mount Everest in Challenger Deep. There would still be over a mile of water above its peak!

The Challenger Deep is named after a British Royal Navy ship called the HMS Challenger. It was the first ship to measure the depths of what is now known as the Challenger Deep.

The trench was measured by “sounding.” This involves dropping a very long line with a weight at the end into a body of water. Today, scientists and researchers use sonar to study ocean depths.

Only four descents into the Challenger Deep have ever been achieved. The first was in 1960 by a vessel called the Trieste. The Trieste was a special kind of ship called a “bathyscaphe,” invented by Jacques and Auguste Piccard. The name “bathyscaphe” is taken from the Greek words for “deep” and “ship.”

The Trieste‘s journey into the trench took almost five hours. Its return to the surface took three hours and 15 minutes. It could only remain on the ocean floor for only 20 minutes. That’s because the extreme pressure caused a crack in one of its windows.

The second descent into the Challenger Deep was made in 1995. This time, an unmanned deep-sea robotic probe named Kaiko made the journey. Kaiko measured the Challenger Deep at 35,696 feet. Kaiko also collected samples from the bottom of the deep.

The third descent into the Challenger Deep took place in 2009. That year, the U.S. Navy sent the Nereus on an exploration. The Nereus is a hybrid remotely-operated vehicle, also known as an HROV.

The Nereus spent more than 10 hours at the bottom of the Challenger Deep. It sent live video and data back to a ship at the surface. Using a robotic arm, the Nereus also collected geological and biological samples from the ocean floor.

Another descent into the Challenger Deep happened in 2012. This time, solo-diver James Cameron descended the DEEPSEA CHALLENGER. He collected film footage, along with photographs and samples of water and deep-sea organisms. 

In May 2019, Victor Vescovo traveled to Challenger Deep as part of Five Deeps, an effort to visit the deepest spots of all the Earth’s oceans. There, he collected more samples for science. He also found a plastic bag, which fueled even more concern about the effect of trash on the world’s oceans.

Would you like to visit Challenger Deep one day? It’s full of life forms that look nothing like life on dry land. It could be an amazing experience! But it may be quite a while before more people can make the journey. Currently, more people have been to the Moon than to Challenger Deep!

Standards: CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1, CCRA.W.2, CCRA.W.4, CCRA.L.1, CCRA.L.2

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