Along the coast of northern California (rent a car and drive the coast if you can) you'll find the Redwood National and State Parks area, one of the natural California vacation spots kids love, covering more than a hundred thousand acres. This whole area of California is sort of a Mecca for American nature lovers. It's home to the Sequoia, perhaps more commonly known as the California Redwood, the largest trees in the world. The scenery is breathtaking, and the area is home to several endangered species including northern spotted owls, Steller's sea lions, and the bald eagle. This is one of the best places you could hope to take an outdoorsy type of kid.
