About 200 visitors had to be moved to safe areas on Saturday morning, after three apes got out of their enclosures at the Orana Wildlife Park in Christchurch.
The three male gibbons escaped by swimming across a moat and jumping several metres to the ground.
The park was locked down after a visitor reported seeing the animals where they shouldn't be.
People were made to wait in safe houses, such as the restaurant, for an hour while the apes were rounded up.
Orana Park zoological manager Rob Hall says it's the first escape they've had from the enclosure since it was built about eight years ago, and it's highly unusual for gibbons to swim, as they don't like water.
Mr Hall says the animals are potentially dangerous, but no one was hurt.
He says there will be a full investigation and changes to the enclosure will be made.