Here are a few suggestions for your next trip from Gdynia

In 4 hours, you can reach Warschau, Posen.

In 5 hours, you can reach Łódź, Breslau.

In 6 hours, you can reach Berlin, Krakau.

In 8 hours, you can reach Ostrava.

In 9 hours, you can reach Hamburg, Brünn.

In 10+ hours, you can reach Paris, Budapest, Wien, Stockholm, Prag, Brüssel, Amsterdam, Vilnius, Bratislava, Zürich...