As icebergs drift along in the ocean currents, they are like massive ships - without navigators. Sometimes, their meandering path nears the shoreline and they run aground, remaining lodged there until they melt enough to float free, or the tides change.

The draft of a berg means how deep the base reaches in the water. That's usually about 1/7 to 1/8 of it, so the part you see on the surface is only a small fraction of what is lurking below the waterline.

Seafloor images of shallower areas show deep gouges where the huge masses of ice have ploughed into the seafloor. Given the incredible size of some icebergs, they can be a very powerful "plow", causing considerable destruction and erosion to the ocean floor in the form of deep gouges, scouring and trenches. They literally pulverize everything in their path!

Picture: A diver checks out an iceberg run aground.