Unless you live in Australia, the only place you can see a platypus in action is at the zoo. In the wild, they live near freshwater creeks and rivers across east and south-eastern Australia.

Like any 23-year-old, Mackenzie is relishing having a home all to himself. The Sydney-born platypus is the sole resident — for now — of a new $12.1 million platypus exhibit and refuge that ...