The design of the Osaka Aquarium Kaiyukan is u have one continuous walkway that descends in a slope thru many floors. This means u continue to walk down and have a view of different displays on different floors.
Here is the main tank again....the Pacific Ocean display
The Manta Ray (Manta birostris), is the largest of the rays, with the largest known specimen having been about 7.6 m (about 25 ft) across, with a weight of about 2,300 kg (about 5,060 lb).