McMurdo Sound is a sound in Antarctica. It is the southernmost navigable body of water in the world, and is about from the South Pole. Captain James Clark Ross discovered the sound in February 1841, and named it after one of Lieutenants of his ships Lt. Archibald McMurdo of HMS Terror abandoned in 1845 and found again in 2016. The sound today serves as a resupply route for cargo ships and for airplanes that land on the floating ice airstrips near McMurdo Station. Physical characteristics Wildlife in the sound include killer whales, seals, Adélie penguins, and emperor penguins. Boundary and Extents The sound extends approximately 55 kilometers (34 mi) in length and width, and opens into the larger Ross Sea to the north. To the south, the sound is bounded by the Ross Ice Shelf cavity, to the west lies the Royal Society Range, and to the east is Ross Island. McMurdo Sound is separated from the McMurdo Ice Shelf (itself part of the Ross Ice Shelf) by the Haskell Strait. Winter Quarters Bay lies at the south end of the Sound, and is the southernmost port in the world. Navigability While the sound is navigable, it contains a significant amount of Drift ice, or pack ice, especially along the shoreline of Winter Quarters Bay. 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 escort by icebreakers. Less than 10 percent of McMurdo Sound's shoreline is free of ice. McMurdo Sound during austral winter presents a virtually impenetrable expanse of surface ice. Even during summer, ships approaching McMurdo Sound are often blocked by various concentrations of first-year ice, fast ice (connected to the shoreline), and hard multi-year ice. Subsequently, icebreakers are required for maritime resupply missions to McMurdo Station. Ross Island is the southernmost piece of land in Antarctica that is accessible by ship. In addition, the harbor at McMurdo's Winter Quarters Bay is the world's southernmost seaport (Department of Geography, Texas A&M University). The access by ships depends upon favorable ice conditions. Tourism is increasingly popular in other parts of Antarctica, but remains limited in McMurdo sound due to the extreme sea conditions. Temperatures Cold circumpolar currents of the Southern Ocean reduce the flow of warm South Pacific or South Atlantic waters reaching McMurdo Sound