The Deep takes us on an epic journey into the unknown, a world of crushing pressure, brutal cold and utter darkness. It's the largest living space on our planet; and today, scientists think there’s more life here than anywhere else on Earth. This is our final frontier.
We discover alien worlds, bizarre creatures. Savage hordes of squid hunt in the depths. Coral gardens flourish in absolute darkness. A whale carcass generates a frenzy as slow-moving five metre sharks fight for their first meal in a year.
There are fish that walk instead of swim; worms that feed on bones; shrimps that spend their lives imprisoned in a cage of crystal sponge.
As we go deeper, the sheer weight of water creates almost unendurable pressures. Yet even eight kilometres down - where the basic chemistry of life was once thought impossible - we find strange new species in the dark.
At volcanic hotspots, micro-worlds blossom into life. The creatures that live here are as alien as the worlds they inhabit. Hair-covered crabs feed on gushing plumes of hydrogen sulphide. Shrimps hover on the fringes of clouds of chemicals, so hot they could melt lead...
...yet one of these geysers may even hold the secret to all life on Earth.
Key story - Methane Volcano
Written by Orla Doherty, Producer
We set out to capture scenes at the extraordinary brine pool - an almost mythical lake at the bottom of the sea - and a death-trap to any unfortunate creature that strays into its toxic waters. For several days, we had been capturing wonderful footage of the scene that lay below us at the brine pool. But in the spirit of exploration, we ventured further west in the Gulf, to a site described to me by Dr Samantha Joye, our expedition scientist and deep sea researcher as a ‘thin curtain of bubbles’.
When we dived there the next day, we found nothing but a barren desert when we first touched down. Then suddenly, just ahead of us, something shot out from the seabed. We watched it rise up into the water column - a huge bubble, the size of a basketball. As it ascended, a trail of sediment fell away from it, drifting back down. Then another bubble, and another. Suddenly, we were entirely surrounded by giant bubbles of methane, erupting from what had been an empty abyssal desert only minutes before. It felt as if we had voyaged to another planet and we nick-named the site ‘War of the Worlds’.
We returned to ‘War of the Worlds’ twice more during our expedition. Both times, there was barely a puff coming from the methane volcano. We had been unbelievable lucky - the deep had given up one of its great secrets, but only the once.
1. Octopus, Feather Star, Antarctic krill - Antarctic peninsular
2. Bluntnose Sixgill Sharks, Scabbard Fish, Sperm Whale, Spider Crab, Toothed Rock Crab, Zombie Worms - The Azores
3. Lanternfish, Humboldt Squid - Chile
4. Venus Flower Basket, Wedding Shrimp Swordfish - Galapagos, Ecuador
5. Cock-eyed Squid, Pacific Barreleye, Anglerfish, Fangtooth, Lanternfish, Siphonophore, Pelagic Sea Cucumber, Longfin Dragonfish, Flapjack Octopus, Giant Tubeworms - Atlantic Coast, USA
6. Bioluminescent Shrimp, Cutthroat Eels, Chaunax - Pacific Coast, USA
7. Ethereal Snailfish, Seapig, Seastar, Bristle Worm - Pacific Ocean
8. White Vent Shrimp, Deep Sea Squat Lobster (Hoff Crabs) - Atlantic Ocean
9. Pyrosome, Oceanic Whitetip Shark - Australia
- The deep sea is the biggest habitat on Earth. Just one part of it, the Abyssal plain, covers more than half of the planet’s surface
- It is though that the clues to the origins of all life on Earth can be traced back to the deep sea
- The deepest part of our ocean is almost 11 kilometres down!
- More people have been to the moon than have been to the deepest parts of our oceans
- Across the series, the BBC film crew has spent more than 1,000 hours in manned submersibles
Predatory Humboldt Squid
Species: Humboldt Squid
- Humboldt are voracious predators. Equipped with a formidable armoury of eight arms and two long feeding tentacles each covered in hundreds of tooth-lined suckers
- They are also cannibals and will readily predate smaller or injured individuals
- Some fish here have a special adaption to allow them to survive these sub-zero temperatures - they have antifreeze in their blood that stops them freezing solid!
The Midnight Zone
- It is perpetually dark in the Midnight Zone. Here, animals use bioluminescence for a range of reasons including, communication within their own species, attracting prey, and confusing predators
- One of the midnight zones most voracious predators - the Fangtooth (pictured below), has the largest teeth in relation to body size of any fish
The Mid Ocean Ridge
- Spanning almost 50,000 miles - the Mid Ocean Ridge is the largest geological feature on Earth
- Over 75% of the volcanic activity on Earth happens in the deep, with almost all of it concentrated on the Mid Ocean Ridge