Oslo to Geiranger prior to Artic cruise

I recommend the 6-7-hour train ride from Oslo to Andalsnes. From Andalsnes, you will transfer to a bus to Geiranger.
The train ride between Dombas and Andalsnes through a river valley is spectacular. The 3-hour bus ride will take you through one of Norway’s most amazing sights— the Trollstigen or “Troll’s Ladder” where you’ll see waterfalls alongside the zigzagging mountain road.

From Andalsnes the VyBus route 25 departs to Geiranger over the Trollstigen road at 0900, arriving at 1200- https://www.vybuss.com/booking/#!/2/1696/1515/2026-07-07/0/BONUS_SCHEME_GROUP.ADULT,1;/

From Geiranger you can connect by ferry and bus to Alesund- see entur (the national route planner)- https://entur.no/reisedetaljer/a4f1f1da-2300-41c9-89f8-b50e854c5308?source=travelResult

You can go direct from Oslo Airport to Andalsnes on the train (with the change at Dombas) at 1425 and 1625 (a Trondheim bound train)

Then on 18 July fly back from Alesund to Oslo.

Or the other way round- fly 16 July Oslo to Alesund, then on 17 July the Geiranger Fjord service boat to Geiranger at 0830 arrive 1130 or a bus/ferry combo, then the Trollstigen bus to Andalsnes at 1300 arrive 1615.

Then 18 July train back to Oslo. In the unlikely event you can't find anywhere to stay in Andalsnes there is a connecting same day train to Oslo at 1629.

Are you spending any time in Oslo at the start? If not, and assuming you're arriving by air, you could fly into Ålesund and then return to Oslo on the scenic train route.

In 2023, after the coastal ferry from Kirkenes to Bergen and a DIY Nutshell from Bergen to Oslo, we flew Oslo to Ålesund for 3 nights. One day cruising the Geirangerfjord and the next day on a fantastic all day small group excursion to Trollstigen and various other stops.

FYI, the beautiful Naerøyfjord is easy to see from Oslo and, IMO, is more spectacular than the Geirangerfjord. You could add a visit to the Stegastein Viewpoint from Flåm for wonderful views.