The Tallinskilja ferry from Hellsinki arrives around 09:30 in Stockholm. We would like to catch a train to Oslo at 11:06. Is that doable and what would be the best mode of transportation? Thanks.
This is really tight , you don't have much slack , I would either take a later train , or stay the night in Stockholm and go the next day . Stockholm is really lovely , I would not blast past it .
If your plan includes seeing Stockholm earlier, and the ferry to Helsinki as well, then you might consider flying from Helsinki to either Oslo or a further point like Bergen, to avoid back-tracking. Try www.skyscanner.com.
Between Stockholm's Tallinskilja terminal and Central train station, Google Maps predicts 10-20 minutes by car/taxi or 40 minutes if you walk to Gardet to take the metro. Rick's book alerted me that the ferry companies operate a shuttle bus, too; see https://www.tallinksilja.com/stockholm-vartahamnen. But I can't guess well (or remember) how long it takes to get off the ferry itself or what the crowd is like.
As I recall , getting off the ferry , down to the bus was realistically close to an hour .