The term "deep-sea" refers to the part of the ocean that is located below the surface layer, typically starting at depths of around 200 meters (656 feet) and extending to the ocean floor, which can reach depths of over 11,000 meters (36,000 feet) in places like the Mariana Trench. This environment is characterized by high pressure, low temperatures, and complete darkness, making it a unique habitat for various forms of life. Deep-sea ecosystems are home to a diverse range of organisms, including bioluminescent creatures, giant squids, and unique species of fish. These organisms have adapted to survive in extreme conditions, often relying on chemosynthesis rather than sunlight for energy. The deep-sea is also a critical area for scientific research, as it holds many mysteries about Earth's biodiversity and geological processes.