For centuries, sailors spoke about a tentacled monster called "the Kraken" that lurked in the oceans.

"There were tales of them pulling ships and men to their death, which may have been partially true, although sailors tell tales," Edith Widder, a marine biologist, said in an interview.

The Kraken, however, might exist — in the form of the elusive giant squid.

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Six years ago, Widder and team of scientists captured the first-ever video footage of the giant squid — which she said can grow to be the length of a four-story building — by attracting the mysterious creature to an electronic flashing lure, which mimicked the glow of a jellyfish.

“That was considered the holy grail of natural history photography,” said Widder.

And after witnessing the long-fabled Kraken up close, she understood why legend had it that they might destroy a wooden vessel back in the day.

“If something comes near them [the squid] they will attach with their tentacles and arms — eight arms and two tentacles — so they could easily pull something down,” Widder said.

More recently, Widder has turned her attention to another type of mysterious cephalopod, smaller than the largest-known species, but still considered giant: the Humboldt squid.

Widder captured footage of the elusive, 7-foot-long creatures and their hunting tactics, emphasizing how little still we grasp about what dwells in the uncharted ocean depths.

A shot of a Humboldt squid's arms and tentacles latching onto Widder's undersea light lure. Image: Oceanx/bbc earth

As Widder found, unlike the solitary Kraken, the Humboldt squids hunt in packs, some 40 strong.

Traveling to remote ocean destinations is hugely expensive, and this Humboldt squid expedition was made possible aboard OceanX’s research vessel, the Alucia.

The organization — which plans to deploy a new vessel in 2019 — captured this footage for the BBC’s’ Blue Planet II series, created through a partnership between OceanX and BBC Earth's Our Blue Planet initiative.

Organizations like OceanX, which seek to bring footage of the deep unknown back the surface, are critical, said Widder, if we want to understand what lurks and thrives in our seas — and how to protect this life from accumulating pollution and deep sea industry.

“Funding for deep sea exploration has been drying up,” she said. “There is hope then, even if our government isn’t willing to fund ocean exploration.”

A hydromedusa jellyfish, documented by NOAA in July 2016. Image: NOAA Office of Ocean Exploration and Research

For perspective, NASA is expected to get around $19 billion in total for its 2019 budget. More than half of this goes to space exploration. The National Oceanic and Atmospheric Administration's (NOAA) ocean exploration budget request for 2018 is $19.4 million.

This isn't to say that the U.S. doesn’t fund any ocean exploration.

NOAA has an Ocean Exploration and Research arm, outfitted with multiple vessels, which deploy remote-operated vehicles to depths miles beneath the surface.

This past April, NOAA surveyed life, shipwrecks, and trash in the Gulf of Mexico. In 2016, the agency spent months exploring the Mariana Trench, Earth’s deepest point, documenting a wealth of wild, tentacled critters.

A map showing U.S. ocean territory, more formally called its "exclusive economic zone." Image: noaa

Even so, most of our planet's oceans remain unexplored.

“Maps of the moon are better than maps of the ocean floor,” Brian Kennedy, a marine biologist and former Acting Deputy Program Manager for NOAA’s Okeanos Explorer Program, said in an interview. “We know so little about the deep ocean compared to other places.”

“I’m often jealous of my fellow forest ecologists,” Kennedy, who is now pursuing research around the remote Pacific Ocean’s Phoenix Island Protected Area, added.

“They can spend weeks, months, or years sitting in a forest. Here we are, maybe spending 6 hours at a time in crewed vehicles, to explore 70 percent of the planet.”

The United States, in particular, has a lot of unexplored ocean territory. The country's ocean territories are about 10 percent larger than the nation's land areas, Kennedy added.

The light lure Widder used to attract Humboldt squid. Image: Oceanx/bbc Earth

“We have an obligation as a society to explore that, and then figure out how to manage it," said Kennedy.

This is especially critical now, as private companies endeavor to mine the sea floor. Mining the sea in shallower coastal areas is already underway.

Using robotic drills and equipment to reach valuable materials from the sea floor, however, has proven more challenging. But, like nearly all technologies, these are progressing. In 2017, Japan tested a tractor-like mining machine in its Okinawa Trough.

Though, one needn’t journey to the ocean depths to impact the marine wilderness.

Although Widder said it’s an “absolute joy” to seek and learn about the still little-know giant squids in our seas, she spends most of her time on the Florida Coast, leading the Ocean Research and Conservation Agency, which seeks to vastly reduce the pollutants entering the ocean from land.

Much of this work is done in Florida’s Indian River Lagoon, a place that 30 years ago was mostly unpolluted.

Widder returning to the surface in an OceanX submersible Image: Oceanx/bbc Earth

“In 1989, it was a wildlife wonderland,” said Widder.

Now, the lagoon has been flooded with poorly-treated sewage and agricultural run-off.

“I’ve been watching it collapse with increasing dismay,” said Widder.

“We’re already paying for it,” she added. “There are signs up that say ‘Do not touch the water.'”

More than 70 percent of Earth's creatures live underwater, Kennedy said. Here on the surface, humans may dominate the land. But in the grander perspective, we inhabit an ocean world.

“If an extra-terrestrial were to visit Earth and describe its life, it would be small, semi-gelatinous organisms that live in the ocean,” said Kennedy.