Did you know that the Earth’s longest mountain range is underwater? The Mid-Ocean Ridge system, shown above snaking its way between the continents, is more than 56,000 kilometers (35,000 mi) long. This series of mountains and valleys marks the areas where the Earth’s crustal plates are moving apart. This is where most hydrothermal vents are located. The University of Delaware’s Extreme 2000 deep-sea dive site is in a vent field in the Sea of Cortés off the west coast of Mexico. Map adapted from NOAA.