The Sparta, a Russian fishing boat which stuck ice while in the Ross Sea in Antarctica was rescued after 12 days by a South Korean ice breaker.  The ice tore a hole in the bottom of the Russian boat forcing crew to evacuate in case the boat sank before they could be rescued.  Pretty scarey!  When I visited Antarctica on the cruise ship Marco Polo, a small red helicopter, which was kept on one of the decks, would fly ahead and check out the icy waters before the ship ventured in.