The hippo was seen floating in a river near the zoo.
Zoo officials say he swam over a guard railing after a typhoon hit the area and flooded his enclosure with more than 6 feet of water.
"The hippo's legs are only 20 centimeters long," zoo director Guo Jinxian said. "So it is unable to jump out of the railing. However the hippo was able to swim out of its home as the water level was 80 centimeters higher than the guard railing when we detected it last night."
A seal and two turtles also used the storm to escape, but the zoo says all of the animals were returned safe and sound.
