This is the 2184th most frequent Japanese word.
水族館
Aquarium.
Subject of the sentence, referring to a facility for marine animals.
水族館は多くの海の生き物を見ることができます。
The aquarium allows you to see many sea creatures.
Direct object indicating the destination visited.
休日には家族で水族館に行きました。
I went to the aquarium with my family on a holiday.
Possessive use, specifying events held by or associated with the aquarium.