The 5 Deepest Parts of the Ocean

February 4th, 2019

Deep Sea

Imagine a gash in the Earth's surface that's deeper than Mount Everest is tall. Such giant troughs exist, and they are the deepest places on the planet.

We don't often think about it, but the ocean floor has geographical features just like those on land, such as valleys, plains, and mountains. The fact is, these underwater features can be massive compared to their dry-land counterparts. The very deepest spots, the oceanic trenches, have barely been explored by humans, and those will be our focus in this article.

Oceanic trenches are depressions in the sea floor. Most are fairly narrow but can span many miles. An oceanic trench marks the location where tectonic plates flexed, with one slab slipping under another to form a massive depression.

If we were looking into the top ten deepest spots, the Atlantic Ocean would come into play, since that's where the Puerto Rico Trench and the South Sandwich Trench are located. But the top five deepest places all exist in the Pacific.

What are we waiting for? Let's dive headfirst into this countdown of the five deepest places on Earth!

5. Kermadec Trench: 32,963 ft Deep

The Kermadec Trench is in the south Pacific Ocean and it's the fifth-deepest place in the world. The trench is approximately 620 mi long, with its southern end located north-east of New Zealand's North Island.

Several unique species live in the Kermadec Trench, including a giant amphipod that, at 13" long, is over ten times longer than typical amphipods.

A fish species that's endemic to this trench, and the second-deepest fish, is the hadal snailfish. Inexplicably, there's also a variety of pearlfish that lives in the Kermadec Trench, hanging out at a depth of 27,200 ft, which is about 20,000 ft deeper than any other pearlfish species.

4. Kuril-Kamchatka Trench: 34,587 ft Deep

The fourth-deepest place is the Kuril–Kamchatka Trench in the northwest Pacific Ocean. It is situated off the southeast coast of the Kamchatka Peninsula in the Russian Far East.

The trench was created by the same geological forces that formed the nearby Kuril island arc and the Kamchatka volcanic arc. It extends about 1,800 mi and features a maximum depth of 34,587 ft.

The trench has steep, sloping sides that are, in some places, interrupted by series of steps or terraces.

3. Philippine Trench: 34,596 ft Deep

The Philippine Trench is located east of the Philippines in the western North Pacific Ocean. It is 820 mi long and 19 mi wide, starting at the Philippine island of Luzon and ending around the Indonesian island of Halmahera.

The central part of the Philippine Trench is considered to be an active depression of the Earth’s crust. This trench's deepest point is called the Galathea Depth and is 34,587 ft deep.

2. Tonga Trench: 35,702 ft Deep

The second deepest place on Earth is the Tonga Trench, located in the south-west Pacific Ocean. It's the deepest trench in the Southern Hemisphere and is the locale of the fastest plate tectonic speed that's been measured.

The Tonga Trench's lowest point is called the Horizon Deep, named for the research vessel Horizon from the Scripps Institution of Oceanography. The crew of the specialized deep-sea craft identified this remarkable spot in December of 1952.

1. Mariana Trench: 36,201 ft Deep

The deepest oceanic trench in the world is the Mariana Trench. It's in the western Pacific Ocean, about 124 mi east of the Mariana Islands, and is approximately 1,580 mi long and 43 mi wide.

This trench's southern end features a small valley that has been named the Challenger Deep, and at 36,201 ft, it's the deepest place on the planet.

To put things in perspective, the Mariana Trench could accommodate the world's tallest mountain, Mount Everest, which is over 29,000 ft tall, and there would be room to spare.

It's cold down there at 36,201 ft—the average temperate is about 36 °F. Furthermore, the water exerts over 1,000 times more pressure than is normal at sea level. Even in those conditions, things do live there.

Several microbial critters called xenophyophores thrive in the trench, including a 4-inch, single-celled amoeba. There is even a fish that can tolerate such depths. In 2014, scientists discovered a new species of snailfish that lives at a depth of 26,722 ft, making it the deepest-dwelling creature known to man.