Thalassophile is a word you don't hear very often.

If you know what it means and, especially, if you happen to be one, you're gonna love this special edition of our show.

Simply put, a thalassophile is someone who loves the sea, and the deep blue is where we're headed today, specifically the deepest known part of the ocean.

Start in the pacific.

If you can find the northern Mariana Islands on the eastern part of the Philippine Sea, you're only about 330 miles northeast of the Mariana Trench.

It's located 7 miles beneath the ocean's surface.

It's what "National Geographic" describes as "a scar in the earth's crust".

This trench extends for more than 1,500 miles and it's 43 miles wide on average, so this is a pretty big gouge on the ocean floor.

And if you go to the southern end of it, you'll find its deepest point.

This remote place is called the Challenger Deep.

It takes patience to get there, even after you sail right over it.

The submersibles that can withstand the pressure take hours to dive this deep.

And even though thousands of people have climbed to the top of Mount Everest, which is 5-and-a-half miles higher than sea level, only a couple dozen have reached the 7-mile depth of the Challenger deep, so it's largely unexplored.

But we know someone who has been there: His name is Rob McCallum, he's from New Zealand.

Last April, he and Australian Tim Macdonald became the first people from their countries to dive this record depth.

They were kind enough to provide us with the video you're about to see, and I had the opportunity to interview Mr. McCallum about the experience not long after he hit rock bottom and then resurfaced in the Spring of 2021.

So, hold your breath, and let's dive in.

It's the last, uh... unexplored frontier on Earth.

Um... we know very little about this... this region, what we call the Hadal Zone, which is that area of the ocean below 6,000 meters or 20,000 feet.

You can't just get there in a normal submarine; what sort of vehicle does it take to withstand the pressures there?

That's a very interesting question, because pressure is, uh, entirely relative.

When a spacecraft goes up into space, uh, they're only experiencing a... a pressure change of one atmosphere between the inside of the, uh, spacecraft and the outside.

We are dealing with a pressure diffe⏤differential of around 1,100 atmospheres.

So, we dive in a titanium sphere, which is able to withstand 100,000 tons of pressure.

Just on the hatch, uh, through which we get into the submarine, just the hatch alone, has 2,200 tons, or around 5 fully-laden Boeing 747s, pushing down on it.

That's... that's incredible, I mean, somebody can't go out and... and buy that; how does one acquire a vehicle like that?

This vehicle was made for this specific purpose.

It was designed and built by Triton Submarines in Florida, specifically to be able to voyage down through 7-and-a-half miles of, um, water column to get to the bottom.

And that's why it's got kind of an interesting shape.

It looks like a pillow that's on its side.

And that's so that it can drop down through the water column very, very quickly.

You said very quickly; how long does it take to get to that depth?

It takes around 4-and-a-half hours to get to the deepest point of the world's ocean.

We go down through the water at about 6 feet per second.

And coming back?

Uh, we release ballast weight on the bottom to, uh, to just spring us off the bottom and head for the surface, and so it's about a 3-and-a-half-hour ride home.

What are you seeing when you get to the ocean floor in the deepest part of it?

This is the most fantastic part of, uh, what we're doing; it's true exploration.

You know, we never know what we're going to see.

Uh, every dive has yielded something fascinating, often, something new to science.

Uh, we are seeing, uh, creatures for the first time; we are discovering entire landscapes which were previously unknown.

That's still a full day just in travel time.

So, how much time does that give you on the ocean's floor?

We tried to, uh, stay down for 3-5 hours on the bottom.

You know, it's a big investment of time and energy; it takes the entire team to get this vehicle prepared and get it down.

And, so, we tried to use every minute possible on the bottom.

Our submersible has three view ports, one for each of the occupants, but also one central one that allows us to see down to the sea floor.

But we're also surrounded by, uh, very high definition cameras that are all linked to a screen in front of us and we can look in any direction, uh, outside.

And that's important because we don't really know where we're going; we're almost always the very first humans that have ever been there.

And, so, although we have a three-dimensional map that we've made the day before, we need a very, um, good view outside to see what's coming.

You know, for humans, we don't really fear what we can't, uh, sense.

And, so, when you're in an airliner and you're looking out, you don't naturally think of the wind going past at 500 miles per hour and it's minus 50 out there and there's not enough air to breathe.

You just... I can see a town or I can see a truck.

And the same in the sub; there's no sensation of movement, there's no sensation of sound, um, you can't hear or feel anything from outside.

It's just a very peaceful, relaxing cruise, uh, into the unknown.

I think that we know so little about, uh, the ocean that we barely understand what questions to ask, let alone, um, have the ability to... to understand the answers.

My role and the role of... of the team that I work with is to simply open the door.

This is the first vehicle in all of human history that has the ability to reach the deep ocean, uh, in any ocean at any depth at any time.

It's... it's... it's... a... akin to the Wright Brothers with the first flying machine.

This is just the first baby steps.

I know the technology might be a way away from creating a sort of ocean exploration station that can withstand depths like that.

But we have reported on⏤there... there is more funding and investment in underwater exploration stations.

I mean, how important would you feel those would be as contrasted with, let's say, the International Space Station?

Both are important, don't get me wrong; I'm... I'm not taking a shot at space travel

But, you know, space is a vast void, a vacuum, uh, that so far has proved to be lifeless.

The ocean is nothing like that.

The ocean is full of life, you know, right from the surface all the way down to the very, very bottom.

I think, before we leave home and start exploring the heavens, we should at least, uh, explore our own backyard more thoroughly.

I think that many of the answers to our collective future are going to be found in the ocean, and some of those in the deep ocean.

The answers to how we're going to handle all the carbon in the atmosphere.

The answers to, uh, the dynamics of our ocean and how we can arrest, uh, the decline of the ocean.

But also the things that we might discover in terms of, um, valuable compounds for medicines and that sort of thing.

So, why do you think there's so much interest in space exploration when we could be exploring what we have right here?

I think it's as simple as when we gaze up at the heavens, we are⏤we have a sense of wonder, uh, what's out there, you know, what can we find?

We always look skyward because we're terrestrial mammals; we... we... we look up to the heavens.

When we look into the water, we don't really see that much.

We see an opaque uh, plain⏤plane... uh, platform that we can pull fish out of, maybe go for a swim in, but we don't actually go too far down.

You know, my dive was about 36,000 feet; most humans never get below about 300 feet.

So there's a long way to go yet.

10-second trivia: What is the most abundant fish in the world?

Herring, Bristlemouth, Minnow, or Sunfish.

Scientists believe the most numerous fish in the world are Bristlemouths, or light fishes.

That's our catch of the day; it is surely fun to take a deep dive into such a "marine-teresting" topic.

There are "oceans" of possibilities, sights to see, facts in the "swim" beneath the surface, "schools" of thought...

I mean, what better way to get a "gyro-education" than to "immerse" yourself in a "current" event?

Today's shout-out goes out to Grenada High School located in Grenada, Mississippi.

There is one place we look for the schools we mention; it's our YouTube channel at youtube.com/CNN10.

So, please subscribe and leave your comments on our most recent show right there.

That's all for our show today, I'm Carl Azuz.