Hydrogen energy is a clean, efficient, and zero-carbon energy source. The formation, transportation, and accumulation of natural hydrogen are closely related to plate tectonics. As the only rocky planet in the solar system known to have plate tectonics and liquid water, Earth has unique geological hydrogen generation pathways such as degassing, serpentinization, and water radiolysis. The ocean-floor, which occupies two-thirds of the Earth’s surface, has great potential for natural hydrogen generation through serpentinization, due to the extensive exposure of oceanic crust or mantle along or around microplate boundaries and ocean-floor fissures. Microplate boundaries, submarine plateaus, ocean floor fracture zones, micro-mantle blocks, and non-volcanic passive continental margins are favorable targets for exploring ocean-floor natural hydrogen. The northeastern continental margin of the South China Sea is also worthy of attention. However, it is difficult to establish a unified ocean-floor hydrogen accumulation model due to the significant differences and diversity in the formation, migration, and storage conditions of natural hydrogen in different tectonic settings. The predicted hydrogen sites, whether they can form reservoirs, how they form reservoirs, and the related exploitation and utilization technologies need to be explored in the future.