Caledonian MacBrayne run almost every major island route on the west coast — Mull, Skye (Mallaig–Armadale), Harris, Lewis, the Uists, Barra, Islay, Arran, the small isles. Book vehicles in advance. Foot passengers can almost always turn up. Timetable and live status at calmac.co.uk.

• Any car ferry, June – August. Especially Mull (Oban–Craignure), Harris (Uig–Tarbert), Barra. Sells out weeks in advance.
• Bank holiday weekends. All routes. Locals book a year in advance.
• The Skye triangle (Mallaig–Armadale, Tarbert–Uig). Constant pressure, even shoulder season.

• Foot passengers, almost always. The bike fits too.
• Off-season, midweek on most routes. Roll up an hour before sailing.
• Small inter-island hops — Eriskay–Barra, Berneray–Leverburgh — usually have space.

The ones no one writes about. Western Isles community ferries; the foot-passenger boat from Mallaig to Inverie in Knoydart (no road in, only the boat); the Corran ferry across Loch Linnhe (saves an hour to Ardnamurchan, runs on demand); the small CalMac to Raasay; the Easdale slate-island skiff. Quietest crossings of the trip.

Storms, mechanical days, low tides. It happens. Have a plan B for each ferry day — somewhere on the mainland to sleep. CalMac email you and the timetable on the website is honest. Don't curse the cancellation. The same weather is what makes the place look the way it does.