Bog lakes in Cheboygan County, Michigan are currently being investigated as part of The University of Michigan Biological Station’s Northern Michigan Environmental Research Program (Gannon and Paddock, 1974). They have also been the focus of several limnological investigations in the past (Jewel and Brown, 1929; Gorham, 1931; Welch, 1936; Gates, 1942). These lakes possess the following classical boreal bog characteristics: (1) open water with a marginal, semi-floating mat consisting of sphagnum mosses and heath shrubs; (2) large quantities of humic materials primarily from allochthonus sources; (3) brown-stained water poor in minerals; (4) a false bottom; and (5) poor drainage. The early investigators also considered these bogs to be low in biological productivity. Our studies have confirmed the generally dystrophic nature of these lakes. However, contrary to previous investigators, we have found that these water bodies develop extremely high standing crops of plankton and are undoubtedly high in plankton productivity. The purpose of this paper is to examine the limnological features of Hoop Lake, a northern Michigan bog lake previously uninvestigated. Particular attention will be given to quantitative plankton data, since such information is extremely sparse in the literature on bog lakes.