The deep sea, defined as ocean depths below 200 m, encompasses vast and largely unexplored habitats, such as abyssal plains, hydrothermal vents, cold seeps, and ocean trenches. This environment supports a remarkable diversity of life forms adapted to extreme conditions, including high pressure, low temperatures, and complete darkness. The Deep Sea Biodiversity and Conservation Collection highlights the importance of these ecosystems and the unique adaptations of the organisms inhabiting these extreme environments, ranging from invertebrates like corals and sponges to diverse microbial communities. The Collection includes studies on coral distribution and ecosystem services, trophic dynamics at cold-water coral reefs, and microbial diversity using metabarcoding and metagenomics. Notable findings include insights into hydrothermal vent communities, the role of chemosynthesis in sustaining deep-sea life, and the adaptation of deep-sea invertebrates to varying depths. These studies underscore the critical need for conservation strategies for these fragile and understudied oceanic ecosystems to ensure their sustainability.