Based on the latest information available, the Wisconsin River -- Marietta Boat Launch is a concrete boat ramp located in Grant County, Wisconsin. It services the Wisconsin River, which is known for its excellent fishing opportunities and scenic beauty.

The boat ramp is approximately 20 feet wide and provides easy access to the water for a variety of craft, including motorized and non-motorized boats, canoes, and kayaks. It is also equipped with a paved parking lot that can accommodate up to 25 vehicles and trailers.

According to the Wisconsin Department of Natural Resources, the Wisconsin River is a popular destination for anglers, with abundant populations of smallmouth bass, walleye, northern pike, and other game fish. However, boaters are advised to exercise caution on the river, as it can be subject to sudden changes in water level and flow.

Overall, the Wisconsin River -- Marietta Boat Launch appears to be a well-maintained and accessible facility that provides boaters with convenient access to one of Wisconsin's most scenic and fish-filled waterways.