The fort is located in the Stockholm archipelago northeast of Stockholm city.
Initially, there two waterways leds to the city of Stockholm between the skerries of the Stockholm archipelago - the north one as the main and rarely used south one. Fort Siarö is located just at the entrance to the northern waterway. The fort is clearly visible from the sea ferries that goes to the Swedish capital and back.
There are two ways to get there. To speak about money and time, both are about the same.
1. You can get the steamboat No 2602 Waxholmsbolagets on the pier in Stockholm near the National Museum, opposite the Trekrunur Palace, and sail to the fort in about an hour.
2. Also you can get the bus No 670 from the stop Danderyds sjukhusin Stockholm to the village Östanå (about 50 min), and from there by ferry to the fort (about 10 minutes).