According to the United States Census Bureau, the town has a total area of 3.5 square miles (9.1 km²), of which 0.004 square miles (0.01 km²), or 0.16%, is water.

Lake Waccamaw is a 9,000-acre (3,600 ha) freshwater lake around and on which is held the annual free fitness event, Take the Lake. Participants may either walk the 15 miles (24 km) around the lake, paddle 14 miles (23 km) around, bike 12 miles (19 km) and walk 3 miles (5 km) around, or swim 4 miles (6 km) across the lake, all on Labor Day weekend. No winners are announced, as awards are presented for completion only. Organizers began Take the Lake in reaction to the county being ranked as the least healthy of all 100 North Carolina counties.

In 2012, residents reported, and researchers at N.C. State University confirmed, that the invasive aquatic weed hydrilla had infested 600 acres (240 ha) of Lake Waccamaw.

Lake Waccamaw's water quality contributes to an interesting mix of animal life in the park. Several species are found only in or around the lake and nowhere else on Earth. These species are known as endemics. At Lake Waccamaw, fish endemics include Waccamaw darter, Waccamaw silverside, and Waccamaw killifish. The water also contains a diversity of unusual mollusks. The endemic Waccamaw spike and Waccamaw fatmucket are among the 15 species of mussels and clams found in the lake. And, of the 11 snail species, the Waccamaw amnicola and the Waccamaw siltsnail are also endemics.

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