See how much the landscape of the lake has changed Enlarge Image

When park rangers patrolled the area in the Magallanes region in March, the two-hectare (five-acre) lake was its normal size, officials say.

But last month they found a huge dry crater and several stranded chunks of ice that used to float on the water.

One theory is that an earthquake opened up a fissure in the ground, allowing the lake's water to drain through.

"In March we patrolled the area and everything was normal," said Juan Jose Romero from Chile's National Forestry Corporation, Conaf.

"We went again in May and to our surprise we found that the lake had completely disappeared. All that was left were chunks of ice and an enormous fissure."

Geologists and other experts are being sent to the area, which is some 2,000km (1,250 miles) south of the capital, Santiago, to investigate.

The region is shaken by frequent earth tremors and one idea is that a strong quake which hit the neighbouring region of Aysen in April opened up the fissure in the bottom of the lake.

A glacier specialist, Andres Rivera, told Chilean newspaper La Tercera that the lake's disappearance seemed to be part of the continual reforming of the landscape.

The Magallanes area "has seen interesting changes in the last few decades," he said, noting that the lake itself had not been there 30 years ago.