The Kosmos Road West boat ramp in Lewis County, Washington is a concrete boat ramp with a gravel parking area for vehicles and trailers. According to the Washington Department of Fish and Wildlife, the ramp is 21 feet wide, with a maximum launch grade of 10%.

The boat ramp services the Mayfield Lake, a 2,200-acre reservoir located in southern Lewis County. The lake is used for boating, fishing, and swimming.

The Washington Department of Fish and Wildlife reports that the Kosmos Road West boat ramp is suitable for launching small to medium-sized watercraft, including powerboats, canoes, kayaks, and sailboats. However, it is important to note that there may be seasonal restrictions or closures due to weather or maintenance, so it is always advisable to check the latest information before attempting to launch a boat.