Off the coast of Puerto Rico lies the deepest underwater trench in the Atlantic Ocean. Known as the Puerto Rico Trench, the area reaches a maximum depth of 28,373 feet and marks the fault where two tectonic plates meet. Recently, scientists embarked on a 52-day expedition to investigate the mostly-unknown waters and map a section of the sea floor. Using remote vehicles, they ventured to depths of nearly 20,000 feet, while streaming much of the footage to an online chat room. The expedition yielded incredible results as they saw many rarely-seen sea creatures, and even some that had yet to be discovered. You'll be amazed when you see this footage for yourself.