WHAT: Oso Flaco Lake HIGHLIGHTS:  Natural dunes and wetlands that are protected by the Nature Conservancy; a beautiful area for viewing endemic birds and plants. WHO SHOULD GO: Hikers, walkers and bird watchers. HOW TO GET THERE: From San Luis Obispo take U.S. 101 south to Highway 1; follow Highway 1 south to Oso Flaco Road. WHERE TO PARK:  There is a parking lot with a $4 fee per vehicle. TRAIL CHARACTER and DISTANCE: Two miles of sand and some boardwalk to the ocean; some trails within the dunes are accessible.