  Increasingly common open data and open application programming interfaces
(APIs) together with the progress of data science -- such as artificial
intelligence (AI) and especially machine learning (ML) -- create opportunities
to build novel services by combining data from different sources. In this
experience report, we describe our firsthand experiences on open data and in
the domain of marine traffic in Finland and Sweden and identified technological
opportunities for novel services. We enumerate five challenges that we have
encountered with the application of open data: relevant data, historical data,
licensing, runtime quality, and API evolution. These challenges affect both
business model and technical implementation. We discuss how these challenges
could be alleviated by better governance practices for provided open APIs and
data.
