In the deep ocean, life is concentrated at chemosynthetic oases where primary production is made possible via chemosynthesis at cold seeps and deep sea hydrothermal vents. The non-chemosynthetic regions of the deep are divided into two very different worlds. First is the midwater, where pelagic wanderers tread migratory routes that span entire oceans, and planktonic drifters and their predators take part in bioluminescent light shows. It is separated into zones based on depth, including the sunlight zone (epipelagic), twilight zone (mesopelagic), midnight zone (bathypelagic), abyssal and hadal zones. And below, lies the deep sea floor. A kingdom of mud and ooze, where sessile creatures cling to any solid outcrop and corals craft kingdoms on the seamount crusts. The worlds of the deep sea could not be more different, and yet their stories are fundamentally intertwined. In this episode, we delve into the Twilight Zone.