The man who died at the Hidden Valley Festival was a member of the New Zealand Army who "served New Zealand with pride".

He was Second Lieutenant Tuitu'u Junior Vaiangina, 29.

Vaiangina joined the Army in 2015 and was most recently based at Linton Military Camp.

"He served New Zealand with pride and will be sorely missed by his colleagues and all who knew him," Chief of Army Major General John Boswell said.

The army extended its sympathies to Vaiangina's family and friends, Boswell said.

Emergency services were called to the festival in Matakana, in the northern fringe of Auckland, after he suffered a medical event about 7.30pm on December 27.

In a statement posted to Instagram yesterday, the organisers of Hidden Valley said they were deeply saddened.

"As a live music festival that prides itself on providing a safe and enjoyable experience for all, we are devastated by this tragic event.

"Our thoughts, respect and aroha remains with the family of the deceased at this time.

"The safety and wellbeing of our attendees, artists, staff, security and support team remains our number one priority."

They say Hidden Valley will continue to follow health and safety guidelines set by police and local authorities.