Beachpools are areas of water cut off from main bodies of water in certain ways. The going out of the tide and the going down from heavy storm waves often form temporary pools. A sudden dropping of the water level, caused by the lowering of a lake outlet, may leave permanent beachpools. Beachpools may be built up in bays by the direct onshore action of waves. Such pools are likely to be crescentic, that is, arcs of circles. Alongshore currents, either normal or wind-induced, may start bars in the lee of points projecting out into the lake. Under favorable conditions such bars may come above water, forming spits which may arc around to the land and cut off a pool. This paper is concerned with observed development of such a beachpool at Douglas Lake, the location of the Biological Station of the University of Michigan, in the extreme northern part of the Lower Peninsula of Michigan. The lay of the land, the shallowness of the water to the windward, and the kind of bottom at Sedge Point are ideal for the development of beachpools because of the action of the prevailing winds, which are of the alongshore type.