The Koninklijke Nederlandse Stoomboot-Maatschappij (KNSM) (Royal Dutch Steamboat Company) was an Amsterdam-based shipping company that existed from 1856 to 1981. It was once the largest company in Amsterdam and one of the top ten shipping lines in the Netherlands. The company operated mid-sized freighters that had limited passenger accommodations. At its peak in 1939, the company had 79 vessels. Of these, 48 were lost during World War II.
In 1972 the company changed its name to KNSM BV, part of the parent company KNSM Group NV. In 1981, they merged into Nedlloyd.
The company headquarters building on the Prins Hendrikkade in Amsterdam is still called the Scheepvaarthuis (Shipping House) and is now a hotel.