The investigated part of the Sunndalsøra aquifer is dominated by sandy sediments deposited during the last 2000 years. Owing to the relatively homogeneous aquifer, seawater intrusion into the aquifer is governed by the fjord delta morphology. Freshwater infiltration from two rivers constitutes the major groundwater recharge and abandoned river channels are important freshwater discharge areas. The sea water has intruded farthest inland in that part of the delta protected from the inflow of fresh groundwater by discharge to these channels. Chemical data show no evidence of ionic exchange. This reveals a relatively stable position of the mixing zone and that groundwater cycling in the investigated part of the aquifer operates at a shorter time than the gradual freshwater flushing of the aquifer.