E6 to Kungälv, take road 168 for 25 km to the island of Koön, take the 200m foot and vehicle ferry to island of Marstrand. This costs 20 SEK for a return ticket and operates about every 15 minutes during the day. Private cars are not allowed on the island. There are severe parking restrictions on Koön for 500m around the ferry.
* E6 to Stenungsund, take road 160 and then 169 for 25km to Rönnäng on the island of Tjörn, take the 5km foot ferry. Rönnäng is a small place with limited parking.
using your own boat or yacht - Marstrand has a popular tourist harbour