Investigators said the 18-, 20- and 21-year-old suspects, whose names weren't released, broke into the Sea World in Main Beach on Queensland's Gold Coast after it closed Saturday, swam in the dolphin enclosure and made off with Dirk, a 7-year-old fairy penguin, The Australian Eye reported Friday.
Police said the penguin was recovered, tired but unharmed, after a couple saw him in a shallow estuary Sunday.
"They heard a scuffle in the water and this penguin came out onto the sand," said Trevor Long, Sea World's director of marine sciences. "They thought it was very, very unusual, so they got on to their iPhone and Googled 'lost penguin.' That came up with the story and from there they were able to contact us."
Long said the couple reported the penguin appeared to have been chased out of the water by an animal that may have been a shark and was then chased on land by a dog.
Police said the three suspects, who were arrested after officers received a tip that they had bragged about their crimes on Facebook, were charged with trespassing, stealing and unlawfully keeping a protected animal.