Take a bus or taxi form the International Airport Münster-Osnabrück (approx. 25 min). Dortmund Airport is only about a 30 minute drive away.
By bike? Münster is a bicycle town and easily reached from all surrounding cycling routes.
Yes, Münster can easily be reached by boat: Via the Dortmund-Ems-Kanal you can reach the harbour and from there it is an easy walk to the city center. Between Hamm and Münster you can take a passenger ship on certain occasions (Info at the Wasser- und Schiffahrtsdirektion West, ph. ++(49) (0)2 51/27 08-0).