Oceans cover three quarters of the Earth’s surface, so it’s no surprise that three quarters of volcanic activity happens on the sea floor. Understanding those volcanoes has ramifications for everything from climate science to the evolution of life. But studying volcanoes covered, in some cases, by miles of water is no mean feat. So it’s also no surprise that there are still plenty of discoveries yet to be made and questions remaining to be answered.

Until recently, scientists thought that the explosive eruptions we see on land would be impossible in the deep ocean because of the frigid temperatures and extreme pressure. But in 2006, a NOAA-led exploration of the Mariana Arc in the southwestern Pacific Ocean captured video of a volcano spewing rock and gas more than 500 meters (1,800 feet) below the sea surface. Then, in 2009, another team captured video of an even deeper eruption - 1,200 meters (4,000 feet) down.

Dr. Julie Huber, an assistant scientist at MBL, was a member of both the 2006 and 2009 teams. She joined me to talk about the excitement of witnessing a deep sea eruption, why undersea volcanoes are important, and her passion for studying the microbes that they support.

WATCH: An Underwater Volcano in Action