No worries, you can get both pizza and hamburgers in Åland

There isn't a single McDonald's in Åland. But there are several pizzerias and hamburger restaurants in Mariehamn. The Finnish chains Hesburger and Koti Pizza can be found in the town centre.
If you want a pizzeria with more of a restaurant feel, you can go to Åland's oldest pizzeria, Fantasia, a few hundred yards north of the town centre. Another option is La Strada in the walking precinct and Adlon Pizzeria och sportsbar at the Hotel Adlon.
Outside Mariehamn it is easier to find places to eat in the summer. In the winter you'll find restaurants, for example, in the Godby Hotell. If nothing else is open, you will usually be able to pick up something to eat at a petrol garage shop.