Hamurana Spring

Hamurana Spring is the deepest natural fresh water spring on the North Island of New Zealand. Located to the north east of Lake Rotorua, the spring emerges from a rocky area within a Department of Conservation reserve. The spring is 920 feet (280 m) above sea level and is approximately 15 metres (50 ft) deep. It produces an estimated 4 million litres of crystal clear water per hour at a fairly constant temperature of 10 degrees Celsius. The spring flows as a stream for approximately one kilometre before joining Lake Rotorua. In summer the stream is home to rainbow trout who prefer the cooler temperature of the spring water.

"Source"

Info. obtained from information available at the site of the spring.