Thanks for the comments. I still like Panorama Factory a lot, works great. For this photo I took 11 shots in portrait orientation with my 55mm lens, on a tripod, 4 seconds each shot.
Milfontes lies on the river Mira estuary (the sea is right on my back for this shot), the least polluted river in Europe (no factories exist along it). It is quite busy during the summer, since it has both river beaches and sea beaches. Much more quiet these days.