Two sandy peninsulas pinch the narrow mouth of 14-mile-long Humboldt Bay, in northwestern California. Edging the cities of Eureka and Arcata, the bay has recently seen cleanup and redevelopment projects, and gradually more shoreline access. South Spit contains one of northern California's longest unbroken duen fields, nearly 7 miles. Its rumpled landscape, punctuated with clumps of beach grass, offers secluded picnicking and, in spring, great driftwood collecting. To get there from ...