San Sebastián Aquarium The Donosti Aquarium or San Sebastián Aquarium is located in one of the most emblematic areas of in the city of San sebastian: the harbor, right next to San Sebastián’s old quarter, and just a few minutes from the city center. The Aquarium is one of the cities most popular attractions, attracting over 300,000 visitors annually. There are other larger and more famous aquariums in Spain, wether it be L’Oceanogràfic of Valencia