BETTER LIVING THROUGH CHEMISTRY!!!

The density of ice (assuming pure, with few gases impregnated within it) is 0.917 g/mL. Comparatively speaking, the density of oceanic salt water is 1.025 g/mL. That means the ice's specific gravity (or relative density) is 0.895 (no units here since the measurement is a proportional one). This would also be the proportion of ice that is hidden (always a profound realization, especially for such a large berg so close to shore).

For those who wonder at my using ice that is "pure", rather than ocean water, it is because the salt does not "freeze" with the water; the ice freezes separately. This does not mean the water would be entirely pure, since some salt water (and salt and other stuff) can become trapped by the ice as it initially froze. But similarly, the ice is obviously opaque, and that is likely the result of trapped gases as those gases come out of solution while the ice is freezing. It would be quite difficult to account for both factors without a physical analysis, so for the sake of discussion, I am assuming (making an ass out of U and some guy named Ming) that both factors cancel out.

So, if you're stranded without water in the Arctic, you can melt the ice and drink it. It may be salty, but not so much that your kidneys cannot handle it.