Emergency Services flew to the scene of the accident around 1.50pm today.
The man's body had already been retrieved from the lake by the members of the climbing group he was part of, when emergency services arrived.
Police said in a statement the man's death will be referred to the Coroner.
Comments on the North Island Back Country Touring Facebook page said a person was rescued from Crater Lake today in a "swift" and "successful" manner.
It is unclear if the man was alive when pulled from the lake.
Hazel Philli commented on the Facebook page that she saw one person limping at the scene of the accident.
Reports from the scene were that a group of climbers slipped near the "Pyramid" traverse of Mount Ruapehu, which is the high point of a circumnavigation around Crater Lake.
