This island is very close to Gothenburg city and possible to reach by public transportation. There are only 1319 people living on the island, but this number increases a lot during summer, especially when the Match Cup Sweden sailing race takes place.
Apart from the sailing cup and the beautiful beaches, the most interesting attraction on the island is the Carlsten Fortress. Marstrand is located in the middle of Sweden, Norway and Denmark. Its strategic location has made the island very attractive during war. When Sweden took the island over in 1658, the king Gustav X ordered that a castle be built on the island. It took 202 years to finish the construction since it was expanded over the years.
There is both an upper and a lower garden of the fortress. It is possible to walk around there and enter some rooms such as the praying room, kitchen, the room of the general and the prisons. Some parts of the castle are connected to each other by dark tunnels. It is very cool and somehow terrifying to see the details in the rooms. The view from the upper garden is unbelievable beautiful. It is the typical Swedish archipelago view.
We visit Marstrand every summer, either for simply enjoying some good seafood at a restaurant, or to do some activities like kayaking or watching the sailing cup. I recommend this place if you are visiting Gothenburg during summer.