Three new species of marine algae are described, one green alga, Codium carolinianum sp. nov. of the Codiales, and two red algae, Trematocarpus papenfussii sp. nov. of the Gigartinales and Gloioderma atlantica sp. nov. of the Rhodymeniales. The genus Gloioderma has not previously been reported from the Atlantic Ocean. All three plants grow offshore on the North Carolina continental shelf.