University of Connecticut geneticist Rachel O'Neill and WHOI deep-sea coral biologist Taylor Heyl describe their dive in the submersible Nadir into Lydonia Canyon on September 18, 2018. In addition to documenting the genetic diversity of corals and other organisms in the Northeast Canyons and Seamounts National Monument, O'Neill is also studying organisms in the ocean twilight zone, or midwater, between 200 and 1,000 meters beneath the surface.