Though oceans make up over seventy percent of our Earth, we know more about the surface of Mars than we do about the deep bed of the ocean floor and the amazing life it sustains. In an attempt to learn more about some of the mysteries that lie in our deep dark seas, four divers recently completed a diving expedition across all the oceans of the world.

Their year-long quest, sponsored by British Television Company, BBC, resulted in 188 dives in some of the most challenging ocean environments, including beneath the ice sheets of the Arctic Ocean and into the mysterious black holes in the waters of the Bahamas . The culmination of all this hard work is 4,000 minutes of incredible, never been seen before footage of life in our oceans. While the film entitled Oceans, Exploring the Secrets of our Underwater World, will be broadcast in November, BBC recently unveiled some of the pictures taken during the expedition.

Among them was that of a Dugong (pictured above) also known as a sea cow. This rapidly declining species with a big round head and a prominent snout, is an herbivore that feeds off the bottom of the seabed. It can grow as large as 11 feet in height and 2,000 pounds in weight. The divers shot these near the coast of Mozambique , where some of the largest populations remain. In ideal conditions, that is when food is plentiful and there are no predators, these creatures can live up to 70 years. But thanks to human activity, their numbers have been reduced greatly, and continue to decline. A large number of them die by getting tangled in nets or due to pollution from oil spills.

The divers also managed to obtain footage of giant Sperm Whales (see above). Distinguished by their large head, these whales have the largest and heaviest brain of any living or extinct animal, weighing as much as 15 pounds for an adult whale. It is amongst the most cosmopolitan of whales and can be found in almost all the oceans, usually in deep-off shore areas. They are the deepest diving mammals in the world - often going in as deep as 1.9 meters for up to 90 minutes at a time. Though they used to be hunted down for food and oil, they have been under protection since 2006 and the biggest current threat to their population is ingestion of human debris, chemical pollution and ocean noise.

Another rare fish caught on camera was the giant Sunfish (pictured), which at their adult stage can weigh as much as 4,000 pounds. Native to the temperate and tropical seas their diet consists solely of jellyfish, which they consume in large quantities. Despite their size, they are very docile and pose no danger to human beings - except of course if a 4,000 pounder happens to land on one!

Other highlights of the dives included a Weedy Sea Dragon (see above), named for the weed-like projections on their bodies that help them blend into the kelp forests they live in, and a green-eyed six gill shark. The divers also found the remains of The Paraportiani, a ship that sank off the coast of East Africa in 1967. All in all, it was an incredible journey of discovery for the divers and the rest of us. The series will be aired in London, UK on BBC 2 starting November 12th. To read more about the divers and see additional photos, check out www.bbc.co.uk/oceans/.