Oslo sits at the head of a hundred-kilometre fjord with a forest behind it and a railway network out of all proportion to the population. Almost everything below is reachable and back in a day.
The islands — free with your ticket
The best day out from Oslo costs nothing extra.
Hovedøya, Gressholmen, Langøyene and the rest are served by ordinary Ruter ferries on ordinary Ruter tickets from Aker Brygge.
Hovedøya has the ruins of a Cistercian monastery founded in 1147 by English monks, beaches, cliffs to swim from and a nature reserve. Ten minutes from the town hall.
Nesodden — twenty minutes, also free
The Nesodden ferry, also on a standard ticket, crosses to the peninsula opposite in twenty minutes.
It is a commuter service and it is a fjord cruise. Walk on the coast path, swim, and come back. If the weather is uncertain and you want to be on the water, this is the answer.
Drøbak and Oscarsborg — an hour
The island fortress whose obsolete guns sank the Blücher on 9 April 1940 and bought Norway its government in exile.
The town is a pretty white wooden one; the fortress is one of the most consequential pieces of ground in modern Norwegian history. Bus in an hour, or a summer boat down the fjord.
Fredrikstad — 75 minutes
Norway’s best-preserved fortified town, on the Glomma estuary near the Swedish border.
Gamlebyen — the Old Town — is a complete seventeenth-century star fortress with the ramparts, moat, drawbridges and grid of wooden houses intact, and it is still lived in. A small ferry crosses the river to it and is free.
Train from Oslo S. A very good half-day and an easy full one.
The Vikings, since the ships are shut
With the Viking Ship Museum closed until the new building opens, the alternatives matter.
Midgard Viking Centre at Borre, in Vestfold, about ninety minutes south. A field of large burial mounds — the largest concentration of monumental Viking-age mounds in Scandinavia — with a reconstructed chieftain’s hall and a museum.
Tønsberg, Norway’s oldest town, nearby.
Both are near where the Oseberg and Gokstad ships were actually dug up, and the Slagen mound at Oseberg can be visited.
The Historical Museum in central Oslo, meanwhile, holds the Viking gold, weapons and the Gjermundbu helmet — the only substantially complete Viking helmet ever found — and is open.
Lillehammer — two hours
1994 Winter Olympics town at the head of Lake Mjøsa, Norway’s largest lake.
Maihaugen, one of the great open-air museums in Europe, with over 200 buildings including the Garmo stave church. The ski jump and the bobsleigh track from the Games. The Norwegian Olympic Museum.
Also Skibladner, the world’s oldest paddle steamer still in service, built in 1856, which runs on Mjøsa in summer.
The Bergen railway — the whole day, and worth it
Oslo to Bergen is around seven hours across the Hardangervidda, Europe’s largest mountain plateau, climbing to 1,222 metres at Finse.
It is routinely listed among the most beautiful railway journeys in the world and the listing is correct. Snow at the top in June, Norwegian wilderness with no road beside it for long stretches, and then the descent to the west coast.
It is not a day trip — it is a one-way journey. But if you are going on to Bergen or the western fjords, take the train rather than the plane, and consider breaking it at Myrdal for the Flåm railway, which drops 866 metres in twenty kilometres to a fjord.
Practical
Ruter tickets cover the islands and Nesodden. Everything else is a separate train or bus ticket.
Vy sells cheap advance fares on the long routes; booking a few weeks ahead makes a substantial difference, particularly on the Bergen line.
Check seasons. Oscarsborg, the island ferries and the Mjøsa steamer are all reduced or closed outside summer.
Sunday services on rural routes are thin. Check the return before you commit.
Into Sweden
Strömstad is about two and a half hours by bus and is what a great many Norwegians do with a Saturday — cross the border and buy food and alcohol at Swedish prices, which are substantially lower.
This is called harrytur and it is an established national habit with its own slightly embarrassed vocabulary. There are quota limits on what you may bring back and the customs post checks.
Gothenburg is around three and a half hours by train and is a genuine city break rather than a day trip.
Choosing between them
Half a day, no planning, no cost: the islands or Nesodden.
A full day, and the best story: Drøbak and Oscarsborg.
A full day, and the best-preserved place: Fredrikstad.
Raining: Lillehammer, because Maihaugen has substantial indoor sections and the Olympic museum is entirely indoors.
Not actually a day trip but do it anyway: the Bergen railway.