It's no secret, December in Gdańsk, (as well as the neighbouring cities Sopot and Gdynia) is all about Christmas! As with Poland in general, the week following Dec 24th (Christmas Eve, the season's most important day for Poles) are various cultural and religious observances that climax on New Year's Eve. The seasonal buzz really begins at the end of November with the opening of the Christmas Market in Gdańsk Old Town. So how does it all look?
What happens during Christmas & New Year's in Gdańsk?

If you're visiting the Tri-city around this time and are unsure of what else is you can do in the cold weather, Check out 'Things to do in Winter in and around Gdańsk'.
Traditional Polish Food & Celebrations in Gdansk
Not surprisingly, Poland celebrates Christmas Eve by eating! Wigilia, the feast of Christmas Eve, officially starts when the first star in the sky is spotted. Bad news if you don’t like Polish cuisine: dinner consists of 12 courses – one for each apostle. Abstaining from meat consumption, with the exception of seafood, is a notably-Catholic observance at various times of the year and, for this reason, you'll see plenty of fish on the Wigilia menu as well as cabbage, mushrooms and dumplings. Fortunately, coastal Pomerania has access to wonderful Baltic fish, so there's no better place in Poland to celebrate Christmas! In Kashubian households, a traditional 'whitewashed' fish soup with sour cream and noodles is served instead of Barszcz (Beetroot Soup) and later a sweet birch soup from dried cherries, pears, apples and plums is served.