Overview: More than 70 percent of Earth is covered in water, but we've only explored roughly 5 percent of it. We've roamed even less of our solar system. Now, armed with some of the latest advances in technology, we join scientists on a voyage into the unknown - from the far reaches of space to the extreme depths of our oceans - where new discoveries have experts questioning everything we know about the universe, and ultimately ourselves. An alternate name of the episode: To the Extremes