The Glacier Express: what to expect (and how to book it right)

It's billed as "the slowest express train in the world," and that's exactly the appeal. The Glacier Express crawls across the Swiss Alps from Zermatt to St. Moritz (or the reverse) over about eight hours, through 91 tunnels and over 291 bridges, topping out at the Oberalp Pass (2,033m). You don't take it to get somewhere fast. You take it to sit in a panoramic carriage and watch the most concentrated stretch of Alpine scenery in Europe slide past the glass.

Here's what the day is actually like, and how to book it without the common mistakes.

What you'll see

The route links two of Switzerland's iconic mountain resorts and threads the valleys between them: deep gorges, the Rhône valley, the spiralling climb to the Oberalp Pass, the Rhine gorge (Switzerland's "Grand Canyon"), and the famous Landwasser Viaduct, the curved six-arch bridge that's on every postcard. The panoramic carriages have huge curved windows running up into the roof, so you see the peaks, not just the valley floor.

Booking: the one thing you must not skip

The Glacier Express requires a compulsory seat reservation on top of your ticket or rail pass. This is the single most important thing to know:

• If you hold a Swiss Travel Pass, Eurail or Interrail, your travel is covered — but you still must pay and book the seat reservation separately, and seats are limited.
• Reservations sell out, especially in summer and peak autumn. Book weeks ahead for high season.
• Without a reservation you cannot board, pass or not.

Classes: is Excellence worth it?

• Second class — perfectly good; same windows, same views.
• First class — wider seats, more room, worth it on an eight-hour day if the budget stretches.
• Excellence Class — premium: a guaranteed window seat, a multi-course meal, welcome drink, concierge service, at a steep price. Lovely if it's a special trip; not necessary to enjoy the route. The views are identical from every class — you're paying for comfort and food, not scenery.

A hot lunch is served at your seat in all classes (orderable onboard), which is part of the experience.

When to go

• Summer (June–September): green valleys, wildflowers, long days, busiest — book early.
• Autumn (October): larch trees turn gold; arguably the most beautiful and a touch quieter.
• Winter: a snow-globe ride through white peaks — magical, and the resorts at each end are ski destinations. Some find it the most atmospheric season.

There's no bad time; the scenery just changes costume.

Honest tips

• You don't have to do the whole eight hours. The Chur–St. Moritz / Andermatt sections include the most dramatic stretches (the Landwasser Viaduct, the Rhine gorge). A shorter leg still delivers if time's tight.
• Sit on the right side travelling Zermatt→St. Moritz for many of the best valley views (it varies — either side sees plenty).
• Phones and cameras struggle with the curved glass glare; just watch with your eyes for stretches, not a screen.
• Connect it to the resorts: Zermatt (car-free, under the Matterhorn) and St. Moritz are worth a night either end rather than a rushed in-and-out.

Book the reservation early, pick any class you can afford, and let the slowest express in the world do its thing.