Narrator: The sea covers seventy percent of the earth’s surface. But this diver won’t find many grim faces in these warm shallows.

Rabbitfish and clown triggerfish; their bright markings make them appealing to our eyes.

Around these corals there’s one fish so cute that it even starred in its own animated adventure.

A sea anemone is home to clown fish; we’ve found Nemo!

A school of bumphead parrotfish. They’ve been known to use their lumpy heads to ram into the reef – breaking off bits of coral to eat.

But we’re after a stranger character.

A giant frogfish.

The sponge-like shape and color are perfect camouflage, and their spatula-shape fins can help keep them perfectly still; they’re a phenomenal ambush predator.

Any small fish swimming into the reach of those telescopic jaws will be sucked up in a flash.

Another ambush predator with intricate markings; even the pupils of its eyes are disguised.

This camouflage breaks up its shape against the sea bottom; but when it moves, it’s easy to see why it’s called the crocodile fish.

But for even funnier faces, we need to leave the tropics for chillier seas.

The giant octopus lives in the cold waters of the Pacific Northwest.

But we’re here to see its neighbors.

Wolf-eels.

They look like grumpy old men of the sea.

To get a good look at them, we need to coax them out of their lair. A few choice morsels will tempt them.

Those curmudgeonly lips have reinforced skin. At the front of the mouth, peg-like teeth clamp like a vice. At the back, massive molars can crush crabs and grind sea urchin spines.

Its off-putting looks are key to its survival. The wolf-eel is nature’s own lobster cracker.

But these wonderful eels aren’t even close to being the ugliest fish in the sea; the deeper you venture into the oceans, the stranger life becomes. The deep sea is the largest and least-explored habitat on Earth… and that’s where we’re going.

At 600 feet, we’re venturing into a brand new world. Some extraordinary creatures have evolved to thrive here: comb jellies, sea butterflies, and ghostly squid.

At 3,000 feet, ninety percent of all creatures produce their own light. This scintillating jellyfish could attract some of the grim predators of the deep.

This squid too could soon be a meal for a monster.

A capture jar on the sub draws in a bizarre-looking oddity that seems to come straight from a nightmare… a gulper eel.

Food is scarce down here, but this eel can maximize its meals by swallowing prey larger than itself; it’s got the biggest mouth in relation to body size of any vertebrate. The contents of the eel’s stomach will reveal its diet, but no one has ever seen it feed.

The sub captures a needle-toothed viperfish, and brings back a ghoul’s gallery of images.

A hatchetfish with bulging eyes…

A deep sea anglerfish…

The well-named fangtooth…

One viperfish fleeing from another…

These are creatures that will never see the surface.

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