Showcasing flora and fauna of the Adriatic Sea, Dubrovnik's aquarium might be modest in content and overpriced, but set in the cool stone vaults of Fort St John’s ground floor, it makes for a lovely escape from the scorching heat and crowds, especially if you've got kids in tow. It's run by the University of Dubrovnik's Institute for Marine & Coastal Research, and serves as a rehabilitation centre for injured sea turtles.