I am looking to calculate the shortest distance between two points inside SQL Server 2008 taking into account land mass only. I have used the geography data type along with STDistance() to work out point x distance to point y as the crow flies, however this sometimes crosses the sea which i am trying to avoid. I have also created a polygon around the land mass boundary I am interested in. I believe that I need to combine these two methods to ensure that STDistance always remains within polygon - unless there is a simpler solution. Thanks for any advice