Tromso Outdoor provide both equipment for rent & purchase, and guided activities from short taster sessions to longer duration. Situated in the city centre they offer cross country skiing, snow walking/hiking, mountain biking, etc., and speak fluent English. I did half day snowshoe walking in the nearby mountains, with their superb guide Kasia. Wish I had had more time to try other activities, like renting one of their mountain bikes with winter studded tyres, which looked great fun.
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