Triangle Lake Bog or Triangle Lake Bog State Nature Preserve is a 61-acre (25 ha) state nature preserve in the U.S. state of Ohio.

It is located in Rootstown Township, south of Ravenna.

It is home to a number of plants including the round-leaved sundew, leatherleaf, highbush blueberry, large cranberry, poison sumac, sphagnum moss and catberry.