For the Douro, I’d pick the Scenic Azure. It’s a small ship built specifically for the narrow and winding Douro, carrying up to 96 passengers. It’s the only vessel of its kind in Scenic’s fleet, with a modern, uncluttered design and a compact, easy-to-navigate layout. Despite its small size, there’s a good sun deck with a small vitality pool and a short walking track, and a lounge and bar that work well for a drink before dinner.

Cabins come with butler service, though for me much of the appeal is in exploring ashore. Excursions are included, but you can also go at your own pace using GPS headsets loaded with walking tours – I find this the ideal way to explore Porto’s back streets at my own pace. I also love taking one of the ship’s electric bikes out for a gentle ride along the river.