An adjustable fin apparatus adjustable between a first expanded position including a pair of inner elongated blades 12 and a pair of outer elongated blades 14; the blades 12, 14 are mounted to a blade housing portion 16 comprising an upper housing element 18 and a lower housing element 20; the lower blade housing element 20 comprises an elongate shape having a slot 22 formed therein along a portion of the length of the lower blade housing element 20; the inner elongated blades 12 comprise an inner edge 26 and an outer edge 28 and a bore 30 is located at an end thereof; an outer elongated blade 14 defines an inner edge 32 and an outer edge 34; and the upper blade housing element 18 comprises an elongate shape generally corresponding to the elongate shape of the lower blade housing element 20.