One of the Sacramento Valley's best wintering waterfowl destinations, the Sacramento National Wildlife Refuge protects wetlands along the Pacific Flyway and hosts one of the most spectacular bird concentrations in the western United States. From October through February, enormous flocks of snow geese, pintails, and tundra swans descend on the refuge — the sight and sound of tens of thousands of geese lifting off the water is genuinely extraordinary. A six-mile auto tour loop makes the refuge accessible without getting out of the car, though walking trails extend into the wetlands for those who want to get closer. A genuine natural spectacle and well worth the I-5 detour.