Most commonly used to describe a vertical depth zone in the ocean that is found starting 3,962 meters (13,000 feet) below sea level. The abyssal zone lies underneath the bathypelagic zone (the “midnight” zone), which in turn is below the mesopelagic zone (the “twilight” zone).  The suffix pelagic describes a region that is not near the bottom nor near the shore or continental shelf, but rather in the open ocean.

The abyssal zone is completely devoid of light, so organisms cannot photosynthesize to sustain themselves. In the abyssal zone the mentality is eat or be eaten, and creatures there have developed special adaptations that enable them to navigate and find food in the inky depths such as bioluminescence and gaping mouths to capture prey. Since the temperature in the abyss hovers around 4 degrees Celsius, animals must be very cold tolerant as well as pressure tolerant to withstand the tremendous force of the water column pushing down around them. At a depth of 3000 meters, the pressure is 300 times greater than the atmosphere at sea level.

Deep sea submersibles: If you’re going to explore the freezing, bone crushing depths of the sea, you might as well do it in style.

The abyssopelagic zone is dark and pretty far down in the water column.