Sumida Aquarium
This aquarium is located on the 5th and 6th floors of Tokyo Skytree Town’s West Yard area.
There's a combo ticket for the Tokyo Skytree observation decks (350m and 450m) plus the aquarium, which is a good deal. Sumida Aquarium is on the 5th and 6th floors of the Skytree. The space isn't huge, but it has the largest indoor open tank in Japan. You can see sharks, rays, and lots of Japanese marine life.
Meiji Jingu Gaien (Outer Garden)
Meiji Jingu Gaien, the outer park of Meiji Shrine, was established in 1926. It features the Meiji Memorial Picture Gallery and various sports facilities, such as the Meiji Jingu Stadium, where you can enjoy nature throughout the four seasons.
After visiting Meiji Shrine, I took a walk around the Outer Garden to see the ginkgo trees. The golden leaves were in full bloom and the place was packed with people. The scenery was absolutely beautiful and really impressive.