Kristiansund has an opera festival — the Operaen i Kristiansund — which is, improbably, the oldest opera festival in Norway, running each January since 1952. It takes place at the Festiviteten theatre, a handsome early-twentieth-century building in the town centre that survived the 1940 bombing. The festival brings professional productions, mostly from Norwegian and Scandinavian companies, to an intimate and genuinely enthusiastic audience.
If your visit coincides with January, it is worth checking the programme. Tickets sell out quickly for the main performances; the festival also runs talks, concerts, and open rehearsals that are easier to access. Outside festival season, the Festiviteten theatre hosts concerts, film screenings, and occasional productions — a good reason to check the schedule regardless of when you visit.