The results of 385 previously published hydrographic stations in the Bay of Fundy are summarized, and the average distribution of salinity at various depths is derived from these data.The total quantity of river water accumulated within the Bay of Fundy is equivalent to the quantity introduced by the rivers during a period of about 76 days.The exchange ratios for tidal excursion segments of the Bay of Fundy range from 0.17 in the neighborhood of Cape Chignecto to 0.056 in the segment immediately south of Grand Manan. In the upper tidal reaches of the Petitcodiac River and of Minas Basin the exchange ratios are about 0.95.The estuary of the St. Croix River has been studied and calculations indicate that about 15 tides, or 8 days are required on the average to replace one day's river flow. The exchange ration in this case range from 0.905 to 0.30.From a summary of existing data in Passamaquoddy Bay it is calculated that the total accumulation of river water is equal to the quantity introduced by the rivers in a period of about 16 days.