The glacier and iceberg viewing boat trips finished for the season this week with Aoraki Mount Cook Village Ltd general manager tourism Denis Callesen saying "It was predicted that iceberg viewing this season would be the most magnificent in the lake's 35-year history, and Mother Nature did not disappoint."
Three historic, and unprecedented, glacial calvings, massive floating icebergs and many blue-ice sightings were all part of the most magnificent season to date.
"To say its been a once-in-a-lifetime season is an understatement," Mr Callesen said.
Passengers encountered record-breaking calvings, saw ice that had been hidden beneath the surface for more than 300 years and experienced colossal floating icebergs.
Signs it would be an extraordinary season began in early August last year when 250mm of rain raised the lake, lifting thousands of tons of ice across the entire 600m width of the face and causing a spectacular 10-million-tonne ice break, or calving, into the lake.
By August 22, 30 million to 50 million tonnes of ice had crashed into the lake, leaving 20 massive, floating icebergs up to 300m long.
On December 19, a second calving following heavy storms, caused the lake to rise by 5m, providing spectators with even greater viewing of the crumbling, towering ice cliffs before getting up close to touch the new bergs in the water.
On January 13, passengers were treated to an incredible sighting of blue ice when the base of a massive iceberg rolled over. Photographers had just two hours to capture the crystal-clear blue ice before it oxidised on exposure to air and turned white.
On February 22, passengers aboard two Glacier Explorer boats were rocked by 3.5m waves when they watched from a safe distance as about 30 million tonnes of ice collapsed into the lake as a result of the Christchurch earthquake.
Then, on March 28, a one-million-tonne calving took place after a 4.1-magnitude earthquake hit the area.
Mild autumn temperatures and calm conditions allowed the season to operate two weeks longer this year, but the boat trips had now stopped for winter with cold weather and ice making it difficult to access the lake, which will eventually freeze over.
Mr Callesen said passenger numbers were up 9% on last year's record season.
The boat trip has become so popular that next year's timetable during the high season will be altered to accommodate more passengers.
"Safety is always our ultimate priority and we constantly monitor the glacier and icebergs in the lake for any signs of rolling or calving.
Boat touring was limited to 800m out from the terminal face when we suspected it would collapse," Mr Callesen said.
Glacier Explorers plans to reopen its 70-minute boating trips on August 15, weather, lake and road conditions permitting.