Scientists have discovered more than 50 hidden lakes under Greenland ice sheets. For the study, published in the Journal Nature Communications, experts from the United States and the United Kingdom came together. Some of lakes are as long as approximately six kilometeres. The lakes were discovered using airborne radio echo-sounding and the findings will enable researchers understand the water network under an ice sheet and the way it moves. If these lakes were to melt, they would increase the global ocean height by 7 meters!