The penguin turned up at Peka Peka Beach on New Zealand's North Island last week, the first time one has been seen in New Zealand in more than 40 years. Typically, emperors spend their entire lives in and around Antarctica.
The bird is being called "Happy Feet" after the lighthearted 2006 movie.
At first, Happy Feet seemed fine, but as the week progressed, the bird became more lethargic. It ate a lot of sand, apparently mistaking it for snow, which emperor penguins eat in Antarctica to hydrate themselves during the frozen winters.
By Friday, conservation officials decided its condition had worsened to the point that it would likely die without help. So they transported the penguin in a tub of ice to the Wellington Zoo.
Veterinarians flushed its throat and stomach with water to remove sand on Friday and Saturday. It remained on an intravenous drip and faces a third flushing on Monday to remove more sand from its digestive system.
Meanwhile, a businessman has offered to take it by boat to Antarctica next February.
Happy Feet is estimated to be about 10 months old, and was probably searching for squid or krill when it lost its way. Experts have yet to determine whether it is male or female.
Emperor penguins are the largest and tallest species of penguin.
The Associated Press contributed to this report.