Maps created with tools like sonar can show the shape of the seafloor, but it's much harder to send cameras down beyond 200 meters, or more than 656 feet, where sunlight begins to fade rapidly and ...

And we’re not even going deep. While the majority of the seafloor lies between 2,000 and 6,000 meters, most dives occur above 2,000 meters. The average dive has grown shallower over time.

What’s down there, anyway? Seafloor mining could target three kinds of metal-rich deposits: nodules, crusts and mounds. But right now, it’s all about the nodules.

Making matters worse, nearly two-thirds of all visual seafloor observations have taken place within 200 nautical miles of just three nations: the U.S., Japan, and New Zealand.

The percentage of seafloor visually glimpsed by humans compared to the US east coast. (Bell et al., Sci. Adv. , 2025) The total seafloor visually glimpsed by humans compared to the nation of Belgium.

Impact on seafloor organisms In the deep sea, where sunlight can't penetrate, organisms on the seafloor lack enough energy for photosynthesis. Instead, deep-sea microbes use the methane or ammonia ...