The surface of Earth is covered 70 percent by oceans and seas, so it might come as a surprise that 95 percent of oceans and 99 percent of ocean floors remain unexplored. This means less than a dismal five percent of oceanic marine life has been discovered or investigated. How is that possible? Because the average ocean is 14,000 feet deep—2.65 miles of darkness. At its deepest, you find the Challenger Deep—36,200 feet beneath the surface—at the western Pacific Ocean by the Mariana Trench's southern end near Guam. Due to the sheer intensity of the ocean's depth, only about 556 feet—or the size of one Washington Monument—has been extensively explored. Millions of dollars in funding or personal investment are necessary, along with lots of time, resources and manpower, to conduct a more thorough examination of oceans. More than likely, the majority of the world's underwater oceanic life will remain a mystery forever. However, the quest to get to the heart of the sea has made plenty of amazing discoveries along the way. The Lost Kingdom of Cleopatra, a mysterious and haunting object at the bottom of the Baltic Sea, regions with rivers, leaves and trees and historical wreckage from vessels like the Titanic have all been captured on film by oceanographers and dive crews.
With the overwhelming majority of the ocean left yet to explore, there are sure to be hundreds of thousands more incredible discoveries that lie ahead. So just how far will we be able to push the limits of underwater exploration? Only time, money and technology will tell. Until then, check out this amazing footage to learn more about life at 20,000 leagues under the sea.