Automatic Identification System [AIS] data is collected from all larger ships and freely broadcasts. Several websites allow the public to track ships in real-time all over the World. When AIS data is stored it allows maritime organizations to accurately monitor how the sea is used. In this talk, we look at how historical AIS data can be used for a wide variety of purposes such as depth models and fuel consumption estimation. Using AIS data for analysis is not always straightforward because data may be missing and the data contains errors. In the talk, we cover how to identify and deal with common errors found in AIS data.