Rick's 2017 Krakow, Warsaw and Gdansk book references the new World War II museum in Gdansk but states that it will open in 2017 or 2018 and doesn't include an address (it is on one of the maps). It opened in March 2017 and it's fantastic! I am so glad we realized it was open and give it a 1/2 day. This is an extraordinary museum and worth planning a trip to Gdansk even if you weren't otherwise going to go.
The audio guide is very good and very easy to use as it knows where you are in the museum and begins the narration automatically -- definitely pay for the audio guide at this museum! The underground parking lot is very convenient and staff in the museum can validate so your first 3 hrs are free.
Museum of the Second World War
http://www.muzeum1939.pl/en/home-page
Plac Władysława Bartoszewskiego 1, 80-862 Gdańsk, Poland
+48 58 760 09 60
Open Tuesday to Sunday from 10:00 – 19:00; closed Mondays
Free on Tuesdays
Regular ticket - 23 zł (about $5 USD)
Reduced ticket - 16 zł
Family ticket (for maximum 2 adults and children up to 18 years old) - 55 zł
Fegular group ticket (10 people or more) - 23 zł
Reduced group ticket (10 people or more) - 16 zł
Audioguide - 5 zł