Anderson Marsh State Historic Park occupies the southeast corner of the oldest freshwater lake on the North American continent. The largest freshwater lake located entirely within California’s boundaries, Clear Lake has been known to yield lake sediment samples as much as a half-million years old. From late spring to early winter, the marsh is lush and green, its open waters edged by tules and other aquatic growth. Bird watching is rewarding here. Besides fishing, the lake — full of non-native crappie, bluegill, black bass, and catfish — also offers boating, camping, picnicking, and swimming.