When the researchers sent

When the researchers sent

 Now, this first-ever look at the glacier’s underbelly near the grounding zone shows that the ocean is attacking it in previously unknown and troubling ways.

 a remote-operated vehicle, or ROV, down the borehole and into the water below, they found that much of the melting is concentrated in places where the glacier is already under mechanical stress — within massive cracks called basal crevasses. These openings slice up into the underside of the ice.

Even a small amount of melting at these weak spots could inflict a disproportionately large amount of structural damage on the glacier, the researchers report in two papers published February 15 in Nature.