The best time for a king crab safari in Tromso, month by month

This is the half of the year most people picture when they book a king crab safari in Tromso, and it earns the reputation. The aurora season opens in September and holds through March; the fjord outside town is darker than any street in it, and an evening boat is one of the better places in Northern Norway to be standing when the sky moves.

The polar night runs from the last week of November to the middle of January. The phrase sounds bleak and the reality is the opposite: for four or five hours around midday the sky over the mountains turns lavender and rose, the snow takes the colour, and photographs come back looking like somebody adjusted them. Boats run their normal timetable throughout.

Two practical points. Wrap up, because a deck in January is genuinely cold and the boats hand out insulated suits for exactly this reason. And book early: December to March is the busiest stretch of the Tromsø year, and the small-group trips at $310 and $361 fill weeks ahead.

March is the month that gives you both ends of the deal. The sun is back for eight or nine hours, the mountains hold their snow, and the evenings are still dark enough for the aurora until the third week. People who want one trip that covers everything often land here.

From late May the midnight sun in Tromsø takes over and the character of the trip changes completely. The fjord flattens, the air softens, and a nine-in-the-evening departure runs in daylight with the sun sitting on the horizon rather than crossing it. For anyone uncertain about the sea, the summer weeks are the kindest on this coast.

Summer is also when Kirkenes runs its RIB safari at $279, with 27 reviews at 4.8 and a route past wartime sites on the shoreline. The winter equivalent at $369 needs the ice, so the two swap places around the turn of the season.

People book a winter crab safari half for the crab and half for the sky, so it is worth being precise about the second half. The aurora is a natural event and it keeps its own timetable; what a boat gives you is the best seat available. Twenty minutes out of the harbour the town lights fall away, the fjord goes black, and you have an open horizon in every direction with nothing built on it.

That matters more than most visitors expect. From a street in Tromsø the lights compete with lamp posts and buildings; from the deck they compete with a head torch somebody forgets to switch off. On a clear evening with activity in the sky, the reflection in flat black water doubles the whole thing, and the photographs that come back from these boats are the reason the evening departures book out first.

The sensible way to treat it is as a bonus on top of a trip that stands up by itself. You are out there for four and a half hours on our top pick at $265, hauling pots and eating the catch; the sky either performs or it stays quiet, and the day is worth the fare either way. Guests who book with that expectation come home pleased far more often than guests who book the aurora and treat the crab as the extra.

One practical note for photographers: bring a spare battery and keep it warm in an inside pocket. Cold drains cells quickly on an open deck, and the moment the sky moves is a poor time to discover it.

For the northern lights, September to March. An evening boat out of Tromsø puts you on dark open water with the pots coming up under the sky.

For calm seas and endless light, June to August. The midnight sun weeks are the gentlest on the water and the easiest to book.

For both at once, March. Long days, snow still on the mountains, and aurora evenings holding on until the equinox.