Covering 1500 square miles, the iceberg grounded in 1986 on the ocean floor, but now it is free it is heading into the Southern ocean.
Carving like this, is quite natural. Unfortunately, though this is occurring far more often, and this is a sign of global warming.
It should be noted that as this was frozen sea water, it should not raise ocean levels, as the water was in the ocean before it froze and will return as it melts.