Extreme-depth Water-related optical imaging: Conquering ultra-low illumination environments from epipelagic zone to Mariana trench

Exploring the deep ocean remains one of humanity’s greatest challenges due to extreme darkness, pressure, and light-scattering effects. Traditional acoustic methods lack the resolution needed for detailed imaging, prompting the development of advanced optical technologies. This comprehensive review surveys the latest innovations in underwater optical imaging, from blue-green pulsed lasers to single-photon detectors and AI-enhanced image processing. It examines how these systems are deployed on deep-sea submersibles to capture high-quality visuals in environments ranging from the epipelagic zone to the Mariana Trench. The integration of artificial intelligence further enhances image clarity and detail, paving the way for unprecedented underwater research and exploration.