Sea Clouds

Sea Clouds (海雲, Umigumo) are a special kind of cloud. They are similar to water, which means that you can sail on them using boats (if you´re not to heavy to sink through) or using a Waver or Jet Ski. However, they are still considered to be like an ocean, and as such, they affect Devil Fruit users like a regular body of water would.

According to Pagaya, an element contained in the Kairoseki called Pyrobloin form sea clouds (as well as island cloud, depending on the density of the water) when it absorbs water in the sky.