It is similar in appearance to the eastern cottontail (Sylvilagus floridanus) but is characterized by smaller ears, legs, and tail.

[1] Molecular data analysis from sequencing the mitochondrial 12S ribosomal RNA gene confirms that S. palustris and S. aquaticus are sister taxa under their subgenus.

Adults from the Florida peninsula weigh approximately 2.2–2.6 pounds (1.00–1.18 kg) with a total length upwards of 17 inches (43 cm).

Adults from the mainland regions typically grow larger, weighing up to 3.5 pounds (1.6 kg) and reaching more than 17.5 inches (44 cm) in length.

[5] Three subspecies of Sylvilagus palustris have been identified: Marsh rabbits display a blackish brown or dark reddish dorsal surface.

Rabbits of peninsular Florida typically display darker and redder colors with a cinnamon-rufous nape, feet, and legs.

[5] It occupies coastal lowland areas, swamps, and rivers and is rarely found more than forty miles from the coast.

Normal hiding spots include dense thickets of magnolia, blackgum (Nyssa sylvatica), sweetgum (Liquidambar styraciflua), briers, and cattails.

Typically, they feed on leaves and bulbs of marsh plants including cattails, brushes, and grasses.

Since rabbits lack a crop displayed in ruminants such as cows and sheep, this process is an alternative method for extracting more nutrients from partially digested plant material.

[8] Frequent hiding spots include dense thickets, hollow logs, and stands of cattails and grasses.

[7] When not concealed in dense thickets, the rabbits will stay submerged in muddy water with only their eyes and noses exposed and ears laid back flat.

[14] Because marsh rabbits possess very short hind legs, they typically rely on doubling and turning when running to evade predators.

[7] Birds of prey such as the great horned owl and northern harrier or marsh hawk are the major predators of the rabbits.

For example, South Carolina establishes a hunting season from November 27 to March 2 with a 5 rabbit per day bag limit.

[16] With their diet of mainly aquatic plants, marsh rabbits are considered minor agricultural pests to most economically viable crops.