Qingdao Aquarium = Qingdao Seafood Museum = Qingdao Underwater World. These three names are the same place.
The first two names are used in the past. In 2003, Underwater World was expanded and renamed Qingdao Underwater World.
The trip will take about three hours.
However, Qingdao does have two aquariums, and the other is called Qingdao Polar Ocean World, which mainly displays polar animals and marine animals. You can also go and have a look, which is not a repetition with Qingdao Underwater World.