Kaiyukan

The Osaka Aquarium Kaiyukan is the biggest aquarium in the world, located at the City of port in Osaka Japan.
The walk through aquarium displays marine life in several habitats. The sea creatures which inhabit the aquarium are from the Ring Fire area of the Pacific Ocean. The largest tank holds 5,400 cubic meters of water which is home to about 580 different kinds of fish and 30,000 different kinds of sea creatures.
If you apply for a reentry permit, you can go in and as many times as you want on the same day. After 5pm, you may encounter the nightlife of the fish in the water.

Admission fee
Adults (Over 16 years old) 2000yen
Elementary school & Middle school students 900 Yen
Over 4 years 400 Yen

http://www.kaiyukan.com/language/eng/

▼About 10 minutes from Hotel Universal Port by shuttle boat.