The Oslofjord, extending more than 100km/60mi northward from the Skagerrak to the Norwegian capital, is made up of a series of narrow straits and wider basins. Along its rocky shores, of moderate height, are many little towns and settlements. The western shore of the fjord was one of the earliest areas of settlement, but the trim towns on the west side can also look back on a long tradition. The first settlers here, coming by boat, established themselves around 10,000 years ago, at the end of the last ice age, and thereafter followed the retreating ice ever farther inland. In addition to farming and forestry there has been a lively development of industry, and the coastal towns are the home ports of a large merchant fleet.
Between Fredrikstad and Skjeberg (pop. 13,500) runs the "Prehistoric Trail" (Oldtidsveien), along which are a series of prehistoric remains: rock carvings at Solberg (human figures, solar symbols, ships) and Hornnes (ships with animals' heads on the prow), 200 burial mounds at Store Dal Felt and rock carvings at Begby, including solar symbols, human figures, animals, and men with swords and phalluses (Bronze Age).
The road from Oslo leads down the east side of the fjord to the attractive seaside resort of Drøbak in Østfold county, lying off the main road, with a handsome wooden church (1736), the Treegaarden Julehus ("Christmas House") and the castle of Oscarsborg in the Oslofjord, where the German heavy cruiser "Blücher" was sunk in April 1940.
Beyond Drammen there are two routes - either on a road hugging the coast of the Drammensfjord or on the main road running inland - to Sande, on the Sandebukt. From here the road continues down the west side of the Sandebukt to Holmestrand (pop. 9,000), which has an aluminum plant. The church (1674), on a Y-shaped plan, has stained glass by Per Vigeland (1957). Also of interest is the Holmestrand Museum (history of the town; ships and the sea, etc.).
To the southeast of Tønsberg, off the main road, is Sandefjord (pop. 35,000), on the fjord of that name. A former whaling port, it is now a seaside resort, with a Whaling Museum and a Seafaring Museum. On the harbor, which is the base of a modern merchant fleet, can be seen a monument to the whalers by Knut Steen. Good bathing and sailing. At the south end of the island of Østerøy is a beacon, the Tønsberg Tønne. To the east of Sandefjord is the Gokstad mound, under which the Gokstad Ship (now in the Viking Ships Museum in Oslo) was found in 1880.
Southeast of Horten, on the shores of the fjord, is the well-known seaside resort of Åsgårdstrand, where the painter Edvard Munch lived for several years (memorial museum in "Munchs Lille Hus", Munch's Little House) and where among other things he painted the famous "Girl on the Bridge".