The need to obtain adequate water samples immediately above a lake bottom or at a precisely defined depth is not new. The problem is of particular concern in a large section of central Lake Erie, where dissolved oxygen concentration may be reduced to 1 ppm or less in the hypolimnion and where the metalimnion frequently extends to or within 30 or 60 cm of the bottom (Becton 1963; Cam 1962).It is impossible to sample the hypolimnrtic waters satisfactorily with the usual Nanscn, Kemmerer, and Frautschy bottles (Carr 1962). Although the 500-ml sampler described here was designed, constructed, and used extensively and successfully to meet the particular problem in Lake Erie, it should be equally useful in a varirty of situations.