To help monitor the transport of water within Green Bay and the exchange of waters between the bay and Lake Michigan, current meter moorings were deployed in the bay and in the passages separating the bay and Lake Michigan, from September 1988 to April 1989 (Part I: Winter) and again from May to September 1989 (Part II: Summer). The winter deployment involved 8 current meter moorings, whereas summer included 21 moorings, 3 thermistor chains, and 7 loran-C-tracked drifters (July only). Each mooring held two or three current meters, usually placed at 12 and 20 m depth and 5 m above the bottom. To aid in understanding the winter data, maps of ice concentration and thickness are included in Part I. Although currents under the ice are surprisingly energetic at the lunar semi-diurnal tide and Lake Michigan surface seiche periods, monthly-averaged currents reveal a very weak and poorly defined mean circulation pattern in the bay. Despite partial ice cover, bidaily-averaged currents are strong, burstlike, and mostly outward through Death's Door Passage, and weaker, steadily inward, and slightly warmer through Rock Island Passage. Monthly-averaged summer currents (Part II) show a somewhat anticyclonic circulation pattern in the southern half of the bay, and a persistent inflow below 20 m depth through all four major passages.