Spetses's restaurants can be packed with Athenians on weekend evenings, so you may want to eat unfashionably early (about 9pm) to avoid the crush. Count on spending at least 25€ at any of these places -- unless you are careful. If the price of your fish is not on the menu, ask for it; fish is usually expensive and priced by the kilogram. Liotrivi (tel. 22980/72-269), in the Old Harbor, is a great place for simple grilled fish or makaronada tou psara (fish, tomato sauce, and pasta) or mayiatiko a la Spetsiate (fish stewed with tomatoes and herbs).
For standard Greek taverna food, including a number of vegetable dishes, try the rooftop taverna Lirakis, Dapia, over the Lirakis supermarket (tel. 22980/72-188), with a nice view of the harbor. To Kafeneio, a long-established coffeehouse and ouzo joint, on the harborfront, is a good place in which to sit and watch the passing scene, as is To Byzantino. Or try Orloff, on the road to the Old Harbor, which has a wide variety of mezedes. The island's popularity with tour groups seems to have led to a decline in the quality of restaurant fare.
Spetses has some of the best bakeries in the Saronic Gulf; all serve a Greek specialty beloved on the islands: amygdalota, small, usually crescent-shaped almond cakes, flavored with rosewater and covered with powdered sugar. It's usually served with a tall glass of cold water; you'll realize why when you bite into all that powdered sugar!
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.