Massive ice release into Tasman Glacier lake at Aoraki/Mt Cook National Park

Massive icebergs have filled at least a quarter of the Tasman Glacier Lake after breaking off the glacier. Photo / Richard Bottomley, Instagram

Massive icebergs have filled up at least a quarter of the meltwater lake at the foot of New Zealand's largest glacier, the Tasman.

The lake started to form in the late 1970s as the glacier rapidly retreated - fuelled largely by a warming climate - and it is now about 6km long.

Glacier watchers estimate the latest release of ice from the Tasman Glacier, the ice river that flows past Aoraki/Mt Cook, extends at least 1.5km.

More than three quarters of all the ice volume that existed in the Southern Alps at the end of the Little Ice Age in the mid-1800s had gone by 2016, glacier experts calculate.

But as well as saddening many mountain lovers, the Tasman lake and its icebergs thrill tourists who go out on the water in boats or look on from above the glaciers steep, rocky walls.

A guide, Richard Bottomley, posted an aerial photo of this week's release of ice from the Tasman.

"This is one of the biggest releases of ice from the Tasman terminal that I've seen," he said.

However, Glacier Kayaking owner and guide Charlie Hobbs said it was comparable to earlier releases.

"It's going to be awesome - it's giving us a lot of icebergs."

View this post on Instagram

Over the past 24 hours there’s been major ice collapse action at/in the Haupapa/Tasman Glacier Terminal face/lake . So beautiful yet sad. The terminal lake is more than 5 km long so this puts the scale of the ice collapse into perspective. . . . #christchurchnz #mtcookguidesnz #mtcookglacierguidingnz #nz_mackenzie #mountcook #mtcook #aoraki #nz #purenz #nzmustdo #southisland

A post shared by Mt Cook Glacier Guiding, NZ (@mtcookglacierguidingnz) on Feb 6, 2019 at 7:56pm PST