Café Mokka on the Plaza is Arcata's best coffee house — a warm, cluttered space with mismatched furniture, good espresso, and a consistently relaxed atmosphere. The café has been at or near the Plaza for decades and has the feel of a place that has never tried to be anything other than what it is.
The main draw beyond the coffee is the Finnish sauna out back, which has been running since the 1970s. Private sauna sessions can be booked by the hour; co-ed communal sessions run on certain evenings. It's a genuinely unusual feature for a California coffee shop and worth doing if you're staying in Arcata more than a day. The café also serves food — soups, sandwiches, and pastries — and stays open into the evening.