The trailer for a show that featured Titanic director James Cameron gives a chilling insight into how deep the ocean actually is.

Very deep, in case you were wondering.

You’ll probably have seen some stuff in the news recently about how far down under the ocean the Titanic is, but this is way further than that.

In fact, it’s not much short of three times deeper than that, and James Cameron went down there himself.

He does love a deep sea dive though, doesn’t he?

Cameron was taking part in something he called the ‘Deepsea Challenge’ which is pretty much exactly what it says on the tin.

The tin being a submersible built to withstand the extreme pressures of the deepest parts of the ocean.

National Geographic

As well as a documentary, the whole thing was filmed for a National Geographic show called Long Way Down: Mariana Trench.

In that documentary, they explained that seven miles under the ocean is a very long way.

In fact, it’s deeper down than Mount Everest is up, if you get what we mean there.

A video to promote that NatGeo show offers a glimpse into the terrifying reality of what happens in the depths of the oceans.

For example, as the sub descends, you can learn that 90 percent of all ocean life lives right by the surface.

Nuclear submarines get down to around 800 feet beneath the waves, and the deepest-ever scuba dive was down to 1,044 feet.

Still a long way to go, then.

All sunlight is gone by 3,300 feet, and even whales can’t dive beyond 8,200 feet.

At around 12,500 feet – 12,467 to be precise – is where we find the Titanic.

From there, things start to get weird.

National Geographic

The snailfish, the deepest living fish ever filmed, was seen at 25,262 feet beneath the ocean surface.

Then, it shows that the sub, carrying Cameron, would reach a total depth of 36,070 feet, the deepest part of the ocean – and on Earth - a place called Challenger Deep.

Cameron achieved this feat in a seven-metre submersible called Deepsea Challenger – are you noticing a theme here? – back in 2012.

It took two hours and 37 minutes to get down there on March 26 of that year.

Cameron spent around three hours exploring the bottom of the ocean in the submersible, which is no mean feat given the pressure down there.

National Geographic

It was only the fourth ever dive to the Challenger Deep, and the second crewed dive, beating the recorded depth of the other craft – Trieste in 1960 – by a few feet.

It was also the first solo dive to that depth.

Interesting stuff, but do you really want to go down there?