The west is machair (fertile low-lying coastal plain) with a continuous sandy beach whilst the east coast is mountainous with the peaks of Beinn Mhòr 620 m (2,033 ft) and Hecla 606 m (1,988 ft). The main village on the island is Lochboisdale (Loch Baghasdail), from which ferries sail to Oban on the mainland and to Castlebay (Bàgh a' Chaisteil) on Barra. The island is also linked to Eriskay and Benbecula by causeways. Smaller settlements include Daliburgh (Dalabrog), Howmore (Tobha Mòr) and Ludag.
South Uist is home to the Askernish Golf Course. The oldest course in the Outer Hebrides, designed by Old Tom Morris, who also worked on the Old Course at St. Andrews. The course, which existed intact until the 1930s, is now being restored to Morris's original design, although this is being held up by disagreements with local crofters. Part of the course was destroyed to make way for a runway, and its identity remained hidden for many years before its apparent discovery, but the claim is disputed by many locals.
After a protracted campaign South Uist residents took control of the island on 30 November 2006 in Scotland's biggest community land buyout to date. The previous landowners, a sporting syndicate, sold the assets of the 92,000 acre (372 km²) estate for £4.5 million to a Community Company known as Stòras Uibhist which was set up to purchase the land and to manage it in perpetuity. The buyout resulted in most of South Uist, and neighbouring Benbecula, and all of Eriskay coming under community control.
The proposal for community ownership has received the overwhelming support of the people of the islands who look forward to participating in the opportunity to regenerate the local economy, to reverse decline and depopulation, to reduce dependency while remaining aware of the environmental needs, culture and history of the islands. The company name Stòras Uibhist symbolises hope for the future wealth and prosperity of the islands.
Loch Druidibeg in the north of the island is a National Nature Reserve owned and managed by Scottish Natural Heritage. The reserve covers 1,677 hectares of machair, bog, freshwater lochs, estuary heather moorland and hill. Over 200 species of flowering plants have been recorded on the reserve, some of which are nationally scarce. South Uist is considered the best place in the UK for the aquatic plant Slender Naiad (Najas flexilis) which is a European Protected Species.
Nationally important populations of breeding waders are also present, including redshank, dunlin, lapwing and ringed plover. The reserve is also home to greylag geese on the loch and in summer corncrakes on the machair. Otters and hen harriers are also seen.
There has been considerable controversy over hedgehogs on South Uist. The animals are not native to the islands, having been introduced in the 1970s to reduce garden pests. They now pose a threat to the eggs of ground nesting wading birds on the reserve. In 2003 Scottish Natural Heritage undertook a cull of hedgehogs in the area.
The SEARCH project (Sheffield Environmental and Archaeological Research Campaign in the Hebrides) on South Uist has been developing a long-term perspective on changes in settlement and house form from the Bronze Age to the 19th century. Organisation within Iron Age roundhouses appears to have been very different from 19th century blackhouses in which the dwelling was shared with stock. Stock sharing living space with people is often regarded as a traditional Hebridean arrangement reflecting Norse influence.