Icebreaker in frozen sea near base on Antartica. (Photo by Fritz Goro//Time Life Pictures/Getty Images). The location of this image is Antarctica. Copyright: Time & Life Pictures

The ice-clogged waters of Antarctica 's McMurdo Sound extend about 55 km (35 mi) long and wide. The sound opens into the Ross Sea to the north. The Royal Society Range rises from sea level to 13,205 feet (4,205 m) on the western shoreline. The nearby McMurdo Ice Shelf scribes McMurdo Sound's southern boundary. Ross Island , an historic jumping-off point for polar explorers, designates the eastern boundary. The active volcano Mt Erebus at 12,448 feet (3,794 m) dominates Ross Island. Antarctica 's largest science base, the United States' McMurdo Station , as well as New Zealand’s Scott Base are located on the island’s south shore. Less than 10 percent of McMurdo Sound's shoreline is ice-free.
Captain James Clark Ross discovered the sound, which is about 800 miles (1,300 km) from the South Pole, in February 1841 and named it after Lt. Archibald McMurdo of HMS Terror . The sound today serves as a re-supply route for cargo vessels and for aircraft that land upon floating ice airstrips near McMurdo Station. However, McMurdo Station’s continuous occupation by scientists and support staff since 1957-58 has turned Winter Quarters Bay into a markedly polluted harbour.
The pack ice that girdles the shoreline at Winter Quarters Bay and elsewhere in the sound presents a formidable obstacle to surface ships. Vessels require ice-strengthened hulls and often have to rely upon icebreaker escorts. Such extreme sea conditions have limited access by tourists, who otherwise are appearing in increasing numbers in the open waters of the Antarctica Peninsula. The few tourists who reach the McMurdo Sound find a spectacular scenery with wildlife viewing ranging from killer whales, seals, to adelie and emperor penguins.
Cold circumpolar currents of the Southern Ocean reduce the flow of warm South Pacific or South Atlantic waters reaching McMurdo Sound and other Antarctic coastal waters. Bitter katabatic winds spilling down from the Antarctica's polar plateau into McMurdo Sound underscore Antarctica's status as the coldest and windiest continent in the world. The sound freezes over with sea ice approximately 10 feet (3.0 m) thick during winter. The austral summer causes the pack ice to break up. Wind and currents may push the ice northward into the Ross Sea, stirring up cold bottom currents that spill into the ocean basins of the world. Temperatures during the dark winter months at McMurdo Station have dropped as low as −59 °F (−51 °C) . December and January are the warmest months, with average highs at 30 °F (−1 °C) and 31 °F (−1 °C) respectively (USA Today).

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