TRAIL: Morro Bay State Park Marina LOCATION:  Morro Bay HIGHLIGHTS:  The largest, least disturbed saltwater marsh on the California coastline. HOW TO GET THERE: From San Luis Obispo take Hwy 1 north to South Bay Boulevard, the Los Osos/Baywood Exit.  From South Bay Boulevard, turn right onto State Park Road.  Proceed past the campground and turn left into the State Park Marina parking lot. TRAIL CHARACTER and DISTANCE: An easy 1/4 mile walk allows exploration along the edge of the saltwater marsh.  During low tide, extend your walk into the marsh to observe more than 250 bird species.  Walk through the Heron Rookery, visit the Natural History Museum and view the bay from White's Point.