The ROV Hercules explores the deep sea.
The Caribbean usually conjures images of white sandy beaches and sparkling turquoise water, but beneath the sea's tranquil surface, powerful forces are at work.
A massive earthquake in the Caribbean could trigger a deadly tsunami that would hit coastlines from Puerto Rico to New York, some say, though others say the risk has been exaggerated. A group of explorers set sail on a three-month voyage to investigate these threats in the Caribbean's undiscovered depths.
Led by deep-sea explorer Bob Ballard, who discovered the Titanic shipwreck, the voyage is the subject of a new TV special by National Geographic's Nat Geo WILD, called "Caribbean's Deadly Underworld," which premiered Sunday (May 18). [In Images: Exploring the Caribbean Deep]
"The Caribbean Sea is actually made up of a piece of earth under attack from all directions," Ballard told Live Science.
The massive 2004 tsunami in the Indian Ocean that killed close to 230,000 people was triggered by an earthquake along a subduction zone fault, where two of Earth's tectonic plates collide. The earthquake lifted the seafloor, giving the ocean above a giant shove that generated the deadly waves.
A similar fault exists along the Puerto Rico Trench. The Caribbean tectonic plate is sliding beneath the North American plate at the trench, and such a plate boundary can be very dangerous, Ballard said. Underwater landslides and volcanic eruptions can also cause tsunamis, and these hazards are present in the Caribbean.