Stony Brook is a 8.5-mile (13.7 km)-long subterranean river in Boston. The largest tributary stream of the lower Charles River, it runs mostly through conduits. Stony Brook originates at Turtle Pond in the Stony Brook Reservation and flows through Hyde Park, Roslindale, Jamaica Plain, and Roxbury. It empties into the Charles River Basin just upstream of the Harvard Bridge. Stony Brook is fed by four tributaries, all of which are partially or entirely in conduits as well.