Sumida Aquarium is on the fifth floor of Tokyo Skytree Town, which is directly connected to Oshiage Station. Walk through Tokyo Skytree Town following the signs for the aquarium.
From Shinjuku Station to Oshiage Station:
Take the Chuo-Sobu Line (Local) to Kinshicho Station, change trains to the Hanzomon Line to Oshiage Station (44 minutes, ¥390)From Tokyo Station to Oshiage Station:
Take the Marunouchi Line to Otemachi Station, change trains to the Hanzomon Line to Oshiage Station (29 minutes, ¥200)