The first supermarket from Hotel Port Mahon to downtown Mahon proper, this was a very nice find to…read morestock up for the day while visiting the city, on the way out to visit the island, or returning back.
Small as supermarkets go, it's very well stocked. Drinks, meals to go, or make your own picnic basket. The meats section has a fabulous selection of deli meats and cheeses (Jamon Serrano and Queso Fresco de Maó), which goes well with their selection of breads (a must try is their wheat, full or mini, baguettes, which are good enough to eat by themselves).
Everything food/sundries wise is available for whatever choice on your vacation day, good prices, and a nice location from the hotel. Prices are reasonable, even with the current Euro/Dollar exchange ratio.
Caveat: Good location if you are staying at Hotel Port Mahon, Hostal La Isla, or Hotel Jume. A little bit off to the northwest side of the city to visit for groceries. Best choice still is the city centered Mercado del Claustro market