Aquarium is off the Technoport line, direct shot from hotel to Osaks Aquarium- easy. Hyatt has a great access map, I think it is on the hotel's website, otherwise pick up map from front desk. Also check out the Osaka Wine Museum walking distance to hotel. Save your money and don't pay for the observatory deck at the World Trade Center- go to floor 47 or so, head towards end of hallway to look out windows. Great views from men's and women's bathrooms. A bit scary I know this stuff about the bathroom view, eh? It was passed on to me by United pilot.