Relatively large numbers of Harbour Porpoises were observed from coastal sites in The Netherlands in spring 1994. The recent increase in porpoise sightings, coupled with sightings of several Bottle-nosed Dolphins in Dutch coastal waters, have led to the speculation that these marine mammals may return in Dutch waters. To put these observations in a historical context, however, a short note on sightings of Bottle-nosed Dolphins and Harbour Porpoises from the Dutch coast near Den Helder, published in 1937, is reproduced. It provides an excellent impression of how common these two species were in this area some sixty years ago. Herring was said to arrive in spring to spawn in the coastal zone. A coastal fishery developed and the activity of fishing birds, fishing people and the arrival of Bottle-nosed Dolphins chasing the fish was considered a sign of spring. Herds of twenty to thirty dolphins were observed feeding and the behaviour is briefly described. Differences with the usually solitary and more inshore occurring Harbour Porpoises are described, including diving time (up to 162 seconds in Bottle-nosed Dolphins, up to 60 seconds in Harbour Porpoise) and the presence of suckling calves (only immatures in Bottlenosed Dolphins, females and suckling small calves in Harbour Porpoise).