Sopot does not have its own international bus station so you will either be dis-embarking in Gdynia or Gdańsk bus stations and travelling to Sopot via the local SKM commuter train which leaves from the railway station. In both Gdańsk and Gdynia the railway station forms part of a complex with the bus station meaning that you will not have to travel far to get to the train. See the Getting to Sopot section in Sopot In Your Pocket for details.