From the World Heritage inscription:
Redwood National Park comprises a region of coastal mountains bordering the Pacific Ocean north of San Francisco. It is covered with a magnificent forest of coastal redwood trees, the tallest and most impressive trees in the world. The marine and land life are equally remarkable, in particular the sea lions, the bald eagle and the endangered California brown pelican.
Redwoods are the tallest trees in the world. I was able to see the giant eucalyptus trees of Tasmania which are almost as tall as the redwoods, but they aren’t quite as impressive because they are hardwoods and have a small trunk. In addition to Redwood State and National Parks, you can also see Redwoods as far south as San Francisco in Muir Woods. They are one of the highlights in any trip to California.