Taxi from the aquarium, Shanghai

Hi, arriving (with jetlag) on saturday midmorning i thought i would go the aquarium and just relax before all the tours starts the next day, and just get an idea of the city and feel of it. Im confident that my hotel can get me a taxi to the aquarium (from the hotel) but how easy would it be to get one the other way around? (is it like NY etc. or would i have to call). Im staying at the Greenland Jiulong Hotel so even condering to do it on foot (getting some exercise after 10 hours of flight) but is it possible to cross the river on foot? (bridge, walk tunnel etc or even ferry)...