Just south of Carmel is a place called Point Lobos State reserve- it's one of the best places I've been on the west coast! If you scuba dive, it's some of the best in the world, there's a kelp forest right off the shore where you can dive with sea otters, seals, and sharks. Also, check out Natural Bridges park in Santa Cruz, try to go when the tide's out, you'll be able to walk the coast a lot farther than at high tide, plus the tide pools formed at low tide are amazing- like little aquarirums filled with anenomes, starfish, fish, etc. Also, there's great place to go sea kayaking near monterrey, but i can't remember the name of it for the life of me. That was a lot of fun, the seals and sea otters would come up right to the kayak!