What does the seabed (or seafloor) feel like?

The global seabed has a wide range of textures. Depending on where you are, the bottom of the ocean might be covered in muddy clay, sand, rocky boulders, or other features.

The ocean is full of amazing features, from seamounts to towering hydrothermal vents. Most of the seabed, though, is coated in sediment deposited from above. In some places, that sediment can be several kilometers thick!

The many sources of seabed sediment lead to different textures, thicknesses, and grain sizes. Close to shore, much of the seabed is made of material from land like sand, silt, and mud. These materials are transported to the ocean by rivers and by wind.

Further from land, the story gets more complicated. Some regions of the seafloor are covered in the shells or “tests” of microscopic organisms that died in shallower waters far above. If at least 30% of a sediment is made of these tests, the sediment is called an “ooze.” The portion of an ooze that isn’t made of tests is often fine-grained clay, which can travel long distances in the ocean before settling to the seafloor.

In the most remote portions of the deep ocean, much of the seabed is over 70% clay. This clay is deposited very slowly, which means that these parts of the seabed can appear practically unchanged for thousands of years or more.

While seabed sediments might not be as naturally exciting as underwater mountains, they’re incredibly important to how the ocean works. Sediments are filled with an enormous number of living organisms, including invertebrates and microbes. Seabed sediments are also eventually subducted into the Earth’s mantle, recycling carbon and other nutrients in a long but critical cycle. Studying sediments that have built up over time can even teach us about environmental conditions in the distant past.

“Seabed” and “seafloor” are often used interchangeably. Both refer to the bottom of the ocean!