The Napa-Sonoma Marshes Wildlife Area is approximately 15,200 acres, or nearly 24 square miles of habitat, including open water, mud flats, tidal salt, and brackish and freshwater marshes. It's home to a variety of fish and game that live within this protected area.

A phenomenal place to watch the sunrise or sunset, the Wildlife Area can be accessed from multiple points in Napa County including at the end of Buchli Road and Milton Road in Carneros, at the end of Green Island Road, and at the intersection of Eucalyptus Dr. and Wetlands Edge Drive in American Canyon. Most of the wildlife area is only accessible from boat and the nearest launch is Cuttings Wharf Boat Launch. There are trails open to hikers and bikers that travel along the levees for bird and wildlife watching.

Hunting and fishing are permitted in the marshes.