Kelps belong to a group of plants called algae. Three kinds of algae—red, green, and brown—live in the ocean. Giant kelp is a type of brown algae. Seaweed is a non-scientific name for all large marine algae. Giant kelp, the largest of all the kelps, can grow to 100 feet in length, as long as a 10-story building is tall! It forms complex forests that include other kelps. The forests are home to a very large variety of fishes and other animals.

Because so many species depend on this habitat for their survival, giant kelp forests are very important.