Kelp is a type of marine seaweed. It is a brown algae. There are many different kinds of kelp. Kelp grow in large forests, usually near the surface of the water. It grows in nutrient rich saltwater. Some kelps grow very fast (up to 30 cm a day). Kelp can reach a length of up to 60 metres. The blades are kept afloat by gas-filled bladders.
Kelp plays an important role as food and habitat for fish and other forms. It may be eaten as a vegetable.
Kelp is found in many places. People put it in aquariums. In the Monterey Aquarium there is a large forest of kelp.
In some parts of the Pacific Ocean, sea urchins have eaten so much kelp that the kelp forests become urchin barrens.