Zoo Miami, one of the main tourist attractions in low-lying south Florida, was shut down until further notice.
After almost 11 inches (28 centimeters) of rain in a 24-hour period "the water level got so high that animals that are potentially dangerous -- whether it be big cats, bears, things like that -- could swim across the moat and get out" spokesman Ron Magill told CBS Miami.
"There is a huge public safety issue there," he said.
"Those moats also filled up with water and these are animals that if they fell in the moats could potentially drown, so it's a big threat to those animals," he stressed.
The zoo first shut its doors as waters rose on Saturday.