The riddle of Snow Lake and the glacier with no outlet

When the British explorer Martin Conway stood on top of the 5128m Hispar La pass in the Pakistan Karakoram in 1892, he described the landscape before him as one of the finest mountain views he had ever seen.

He was expecting to see another valley like the one he had ascended up the Hispar Glacier. Instead they found themselves looking down on a vast basin of snow that he named the Great Snow Lake.

From the midst of the snowy lake rose a series of mountain islands white like the snow that buri...