Auckland Zoo will carry out a safety and security review after a man got into the rhino enclosure and bathed in the water today.
Video footage showed him climbing over a barrier and getting into the moat, startling four rhinos before bathing in the water and washing his face.
Auckland Zoo said in a statement that the man stayed in the water for a number of minutes before responding to staff's instructions to get out of the enclosure.
It said the rhinos were "understandably startled" by the intruder and moved quickly to the other end of the habitat where zookeepers were able to safely hold them.
Police said it took a man into custody on Wednesday morning.
It said no people or animals were hurt in the incident.
Auckland Zoo Director Kevin Buley said he was proud of the professionalism that his staff showed.
"We are all very relieved that there were no injuries to either the animals or people as a result of what happened this morning.
"We hope that the man involved gets the help and support that he very clearly needs."
Buley said the rhinoceros area fence was over a metre high and complied with enclosure regulations.
A review would examine whether any changes should be made, he said.