Risen from the Deep

From the introduction: Risen from the Deep is intended for four characters with an average party level (APL) of 14. Characters who complete this adventure should earn enough experience to reach halfway to 15th-level. Tales of a terrible sea monster harassing the shipping lanes has reached the port. This campaign takes place in Arden, although it can be set in your own world. Any party composition should be able to finish the adventure with intelligent play.