We used the Wydmy fast train from Bohumín - get the tickets and couchette reservations well in advance, especially when you want to go during or near weekends. There are two types of coupes - three or two bedded. If the complimentary muffin is not visible, check the cabinet above the washbasin (hidden inside the table in the coupe). The morning herbata is free. The return train leaves too late in the evening (11 p.m.) and ours was 20 minutes delayed, next time consider going further to the north so we can leave earlier.
Current state of all polish beaches; also wsse.
Polish public transport lookup for android (buses+trains)
Public transport in Gdansk - buy enough tickets in advance, they are more expensive from the driver and some stations don't have vending machines.
Tramwaje wodne - F5 only makes sense to board at Żabi Kruk, it only has 50 places and is full immediately; it'd be a shame to miss. The port is the best. Latarnia is nice. Need to visit Westerplatte the next time.
Weather - Windy seems to be better, also contains waves prediction
Maps - mapy.cz with offline maps are unbeatable
Local sport events in Gdansk
Skimboarding - free on Wednesdays
Triathlon Gdansk
Pomorski Klub Orientacji, Harpus
Rodzinne Gry Parkowe na Orientację
Malbork - when going by train, get off at Malbork Kałdowo. Forget the audioguide, the people guides rock. 4 hours might be enough. On the other hand there's reduced entry after 17:15.
Camp Stogi - crowded and the tent area is very hilly. Not really quiet before 10-11 p.m., but we've been to worse. Mosquitoes in the forest