Restaurant Mumm, in a 17th-century house on Søndergade in Ærøskøbing, is the island's smarter dinner option without being formal. The kitchen leans on local produce: Ærø lamb in summer, smoked fish from the harbour, vegetables from nearby farms, and apples from the orchard out back for desserts.
The dining room is small — a few candlelit tables under low beams — and reservations are essential in summer. Service is unhurried, the wine list is short and well chosen, and a three-course dinner here is one of the better reasons to stay an extra night.