The main boat docks are in Brienz and Interlaken. Both towns can be reached by car or by train.
How to get to the boat dock
The main boat docks are just outside the rail station of Brienz, and just outside the rail station of Interlaken Ost. Both places can be reached by car but it's easier by train.
Some other towns where you can board the boats are Bönigen and Iseltwald. Note that the map does not show all the stops as they are different per trip. If you have the time, we recommend to do the complete trip from Interlaken to Brienz. That allows you to see the whole of the lake.