A monofin, for use in swimming, includes a fin shaped like a whale tail, wherein the fin further includes a leading edge and a trailing edge. At least one corrugation is formed in the fin, wherein the at least one corrugation is parallel to a portion of the leading edge. At least one foot pocket assembly may be removably coupled to the fin. The at least one foot pocket assembly includes a foot pocket cover formed to removably couple around a portion of the fin. At least one foot opening is formed in the foot pocket cover and at least one cuff surrounds the at least one foot opening. At least one foot pocket is in communication with the at least one foot opening. The at least one cuff stretches to encompass an ankle of users of many sizes and holds the monofin on the users.