The project uncovered a massive subglacial trench, or valley, that is up to 1.9 miles (3 kilometers) deep and more than 15.5 miles (25 kilometers) across. For comparison, the Grand Canyon is 1.13 miles (1.8 kilometers) deep at its deepest point. In places, the floor of the subglacial valley is more than 6,500 feet (2,000 meters) below sea level.