Marina Mehlbergen is a family-run marina on the Middle Weser near Nienburg, Germany, welcoming boating and motorhome visitors since 1975. With around 130 seasonal berths and seven guest berths, it offers a convenient base for exploring the river and surrounding countryside. Facilities include shore power, fresh-water points, showers and toilets, plus a professional slipway in a sheltered harbor basin for boats weighing up to 3.5 tonnes. The slipway is also available to visiting boaters and anglers.

The marina has 20 motorhome pitches overlooking the harbor, with electricity, Wi-Fi, fresh water, sanitary facilities and waste-water disposal. Dogs are welcome. The Treibgut Store serves marina guests, campers and the local community with baked goods, drinks, snacks and everyday essentials. Visitors can also take advantage of the boating school, which offers training for prospective sport-boat operators. The license-free rental boat Lea is scheduled to return for trips on the Middle Weser in 2027. Located beside the Weser Cycle Route, Marina Mehlbergen also provides access to Nienburg and nearby attractions.