Over his long career, the 71-year-old Rutgers University professor has studied the impact of dumping, oil spills, and other threats to the oceans.
More recently, he spearheaded an ambitious 10-year project to catalog all the living things in the sea. On Monday, that census reported its first results, revealing thousands more species than expected and projecting that many times more have yet to be discovered.
Before all that, however, he had to find a way to get to all that volcanic activity near the Galapagos.
By 1979, he had secured use of the world's most capable deep-diving submersible craft, known as Alvin. And to help locate the vents, he recruited explorer Robert Ballard, who would later become famous for discovering the Titanic.
Grassle and Ballard set out on a real version of the fanciful voyages of Star Trek's Kirk and Spock, seeking out new life.
The world of the vents was not just alive. It was exploding with life: plumes of polychaete worms as bright as roses, rainbow-colored creatures that draped over rocks like spaghetti, mussels the size of dinner plates.
The vent communities were like nothing ever seen on Earth. No one had imagined abundant life in a sunless environment, thriving on geothermal heat and chemistry.
On Tuesday in New Brunswick, in an office lined with photos and drawings of sea life, Grassle lit up with a smile as he recalled the adventure, describing deep-sea creatures the way a child might recount cherished Christmas gifts.
"It was a privilege to be in the sub," he said, "and we wanted as many people to share it as possible." So he arranged to have a filmmaker take footage that was made into a TV documentary called Dive to the Edge of Creation.
