Deep water is any body of water that is at least 65 feet (20m) deep. It is the deep ocean and its associated environments, including the deepest regions of the continental shelves and abyssal plains. Deep water contains a diverse array of biological and physical features, ranging from delicate and brightly colored soft coral fields to dramatic deep sea volcanoes and thermal vents. It is also home to some of the planet’s most awe-inspiring creatures, from giant tube worms and manta rays to huge sharks, whales, and squids.

By definition, deep water is water located beyond the photic zone, which is the region of the ocean where sunlight reaches the seafloor. At these depths, the pressure is incredibly intense, varying from five hundred to several thousand times greater than atmospheric pressure at sea level. This high pressure environment presents several biological and physical challenges for animals that live in the deep ocean, which is why most of them have adapted to survive in this extreme environment.

Many organisms living in the deep ocean have adapted to survive with little or no sunlight, depending on tiny particles of food that are brought down by currents from the well-lit surface regions of the ocean. These animals therefore have unique feeding strategies, such as filter-feeding and scavenging. Some of the most interesting creatures that are found in the deep ocean include the giant squid, six gill sharks, monocephalid fish, and venomous cone snails.

The deep ocean is also home to some of the planet’s most mysterious and hostile environments, such as hydrothermal vents, underwater mountain ranges, and methane seeps. These locations can release toxic gases, toxic metals, and bacteria, making them dangerous for human exploration. In the past several decades, humans have ventured into the deep ocean using special submersibles, such as Alvin, to explore these alien landscapes.

The deep ocean is an essential part of Earth’s biosphere, representing over 90% of the ocean’s total water volume. Yet, despite our immense knowledge of the ocean’s surface, we still know very little about what lies below it. Scientists continue to explore the secrets of the deep ocean, and uncover the mysteries of this alien world.