I was expecting a train to go. But, no matter where I look there is no train connecting the two cities. Nor a bus.
I based my assumption on https://www.rome2rio.com/map/Gdynia/%C5%81eba which states there should be a train. Other sources also refer to trains.
I expected to find the connection on either https://www.intercity.pl/en/ or https://rozklad-pkp.pl/en Both display 'no route found'.
I checked Flixbus and Blablacar, both with no success.
I really want to go to Slowinski Park Narodowy over the weekend. Does anyone know how I could get there - taxi would cost 75€ one-way, according to rome2rio.
UPDATE
I verified the top answer (Cuba).
Currently there are cunstruction works at Lebork - to find the bus, exit the train station to your left. The buses have a sign telling you where they go.