Algerine Swamp Natural Area is an 84-acre protected tract in Pennsylvania within Tiadaghton State Forest, spanning parts of Lycoming and Tioga counties and recognized as a National Natural Landmark. Centered on a glacial bog, it is notable for black spruce and balsam fir, both uncommon in Pennsylvania. The area also supports other tree species more typical of regions farther north in Canada, along with a population of pitcher plants. It can be reached by the nearby Long Branch Trail, a short distance north of its junction with the Black Forest Trail.