Hello VicH
Welcome to MySwissAlps
The Quickest Route
Normally the quickest route from Interlaken to Milan is to take any train for the short ride to Spiez, and then catch a Eurocity (EC) trian train from Spiez to Milan via the Lötschberg base tunnel, Brig and Domodossola.
In normal circumstances the Eurocity trains (which have come from Basel via Bern) run three or four times a day, and take two hours and fifty minutes to get from Spiez to Milan.
Just be warned of two things. Firstly the EC train is likely to be very busy, and seat reservation is compulsory.
Secondly, between 2024 and 2027 Italian Railways are doing a lot of engineering work on the line from Domodossola to Milano. So it is just possible that this work will disrupt your journey.
Highly Scenic Route which I would recommend most strongly.
The times I give below may be slightly different in 2026, but I would not expect a major change.
Catch the 09 04 Luzern-Interlaken Express to Luzern, arrive there 10 55. (Luzern is the German name for Lucerne.) For the best views sit on the right in the direction of travel, and do not change your seat when the train changes direction at Meiringen
From Luzern catch the brown painted ‘Treno Gottardo’ leaving Luzern at 11 18. This train takes the OLD Gotthard railway line opened in 1882. It does NOT go through the world’ s longest railway tunnel, the Gotthard Base Tunnel opened in 2016.
Stay on the Treno Gottardo to its final destination, Locarno, situated at the north end of Lake Maggiore. You reach Locarno at 14 27.
Have a short brake in Locarno. Then catch the 15 22 RE80 train bound for Milano Centrale, arriving there at 17 17 (just as it is getting dark!)
Seat reservations are not required on any of the three trains. All three are ‘workaday’ trains which take people to work, school, shops, appointments, sports events, leisure activities like hiking and skiing etc. etc.
(NB I am British. Swiss public transport- and not just the trains – is way better than British.)
Best wishes
Roger