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# How deep is the ocean

The bottom of the Mariana Trench is the deepest point of our oceans and is known as the “Challenger Deep”, and lies at a depth of around 11km (6.8 miles). So how deep is the ocean you may ask, well deep, very deep. Think of how high Mount Everest is, well the ocean is even deeper, no wonder it took them so long to find Nemo.

Officially 200m (650 ft) and deeper is known as the “deep sea”, but did you know the average depth of the ocean is around 3.5km (2.2 miles).

The bottom of the Mariana Trench is the deepest point of our oceans and is known as the “Challenger Deep”, and lies at a depth of around 11km (6.8 miles). Other trenches that are deeper than 10km (6.2 miles) are the Tonga, Kuril-Kamchatka, Philippine, and Kermadec trenches, all located in the Western Pacific.

Like the Challenger Deep, there are different names for different depths. The “Littoral Zone” is the depth from the ocean’s surface to about a depth of 200m (650 ft), going down to 3km (1.86 miles) it’s called the “Bathyal Zone”, and from 3km (1.86 miles) to 6km (3.7 miles) it is known as the “Abyssal Zone”. Anything between the Challenger Deep and the Abyssal Zone is known as the “Hadal Zone”, named after “Hades”; the Greek kingdom of the Underworld and the god of the Underworld himself.

## Ok, so how deep is it really?

To calculate the depths of the Hadal trenches, bomb sounding was used. Basically, they threw some TNT of the side of a boat, let it explode after it hit rock bottom and measured the time it took for the sound to reach the ship again. So to be honest the exact depth of the Challenger Deep is still hard to calculate.

For now, I’ll just keep my dives to about 30m (98 ft) where sunlight can still reach me.

Check out this great animated video from Tech Insider that puts it all in perspective.

#### Colin

Colin is Padi certified Divemaster, loves diving with the larger marine species around the world, and writing code.

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