You mentioned how much of an iceberg is above the water line because of buoyancy. Is this different for glacial ice since it's more dense? It's my understanding that glacial ice is kind of like the ice equivalent metamorphic rock, it's been compressed by pressure and this is why the light coming through it looks blue (because the molecules in it have been aligned by the squeezing process, or some such thing). Also, Thom doesn't want to think of light as being a fluid, but I'm drinking Coors Light right now, and that has "Light" in the name. Check mate science!