Great Dismal Swamp, a large morass in Virginia and North Carolina, extending 40 m. S. from near Norfolk in the former state, and 25 m. E. and W. The soil consists of black vegetable matter to the depth of 15 ft., saturated with water, yielding to the tread of man. and during a large part of the year covered in many places with stagnant pools. Several small streams flow through it, and in the centre is Lake Drummond, (1 m. long and 3 m. wide, the surface of which is 21 ft. above tide water. The swamp is for the most part covered with a dense growth of cypress, juniper, gum, and cedar, and upon the drier ridges that intersect it are found the beech and oak. Much of the most valuable timber, however, has been cut down, and large quantities have been obtained from beneath the surface, where the fallen trunks have been preserved by the wetness of the soil. The Seaboard and Roanoke and the Norfolk and Petersburg railroads pass through the N. border. The great channel of transportation is the Dismal Swamp canal, made by the assistance of the national government and the state of Virginia, which connects the W. branch of Elizabeth river with the Pasquotank. It is 6 ft. deep, supplied chiefly by Lake Drummond, with which it is connected by a feeder, and passes for 20 m. through the swamp, affording an outlet not only for timber but for much of the agricultural produce of the E. part of North Carolina. Steam power is used upon it, and the tolls amount to about $20,000 a year.

The Chesapeake and Albemarle canal also passes through the swamp, connecting the E. branch of Elizabeth river with Currituck sound, and admits vessels of considerable size. In 1870, 4,382 vessels of all classes passed through it, and the revenue from tolls and towage was $58,734. This canal contains ft, single lock, 40 by 220 ft., and is fed by tidal action. Several minor canals connect the main-land with Lake Drummond. A stage road runs parallel to the Dismal Swamp canal from the N. border to Elizabeth City, X. C Roads are made in the swamp by laying logs 8 or 10 ft. long side by side on the surface of the soil or "sponge." They are passable by mules and oxen, but carrying is done mostly by hand to the creeks and ditches communicating with the canals. - The productions of the Dismal Swamp consist chiefly of ship timber, boards, shingles, staves, railroad ties, and fire wood. It is especially noted for its shingles. A large force of colored men is employed during the drier months of the year in preparing the lumber for market.

Its dimensions were first accurately estimated by Col. William Byrd in 1728, while engaged in surveying the boundary of Virginia and North Carolina. An account of his passage through the swamp has been preserved in the Westover MSS. - Along the coast of North Carolina are the Little Dismal and several smaller swamps, covering in the aggregate about 2,000,000 acres. They were once noted retreats of runaway slaves. (See Bog.)