A mighty iceberg drifts past the ship. More than three quarters of its mass is invisibly hidden under the water surface. Thus, a large safety distance is necessary. Also, the sometimes 70 metre high icebergs often collapse spontaneously and generate small tidal waves.
A special curiosity are green icebergs. They can originate if an iceberg (which is sometimes grown over with algae on its bottom side) partially collapses and turns over. The colour is then indeed grass green.