Aoraki Mt Cook Alpine Village tourism general manager Denis Callesen said the pressure of ice lifting out of the water on the glacier face could lead to a spectacular break-off of a giant slab of ice or "calf" into the lake.
"Sometime soon there's going to be a massive calving.
"If the whole lot goes together, upwards of 10 million tonnes of ice could break off in one hit.
"When that happens we'll have one or more icebergs launched into the lake, creating a huge surge of water.
"It will be a truly impressive sight," he said.
In February last year an iceberg, estimated to be 250m long by 250m wide by 80m high, plunged from the terminal face into the lake.
Boat trips to view the icebergs and the glacier's terminal face are a popular tourist attraction.
