There aren’t too many self-service launderettes aboard a river ship, but a few do exist. New Crystal River Cruises has a self-service launderette. However, most of river ships offer a laundry service similar to that found on cruise ships.
Simply place your items to be cleaned in the furnished laundry bag and fill out the inventory slip. Your room attendant will return your clothes the next day, laundered and folded or on hangers. Note that dry-cleaning is not available. Laundry services are wash and iron, or just iron.
In-room irons are a huge no-no for the fire hazard they present. Sinks are usually large enough to hand-wash items and most shower stalls include a retractable clothesline. Some cruise lines, like Viking River Cruises, permit portable steamers; check with your cruise line to be sure.