If you have 6 hours or half a day to spend in Shetland Islands, here are some suggestions:
1. Visit the Shetland Museum and Archives: This museum provides an insight into the history of the islands and is a great way to spend a few hours. It includes interactive exhibits that take you through the history of the Shetland Islands. Allow around 2-3 hours for your visit.
2. Take a walk along Lerwick's waterfront: Lerwick is the largest town in Shetland Islands, and you can enjoy a nice walk along its waterfront. You will find plenty of cafes and shops, and it's a great way to get a feel for the town. Allow around an hour for your visit.
3. Visit the Broch of Clickimin: The Broch of Clickimin is a historic tower that dates back to the Iron Age. It's located on the outskirts of Lerwick and can be reached by bus or car. Allow around an hour for your visit.
4. Take a boat tour: There are several companies that offer boat tours around the Shetland Islands. This is a great way to see the islands from a different perspective and spot some wildlife. Allow around 2-3 hours for your visit depending on the tour length.
5. Visit the Scalloway Museum: Scalloway is a small village located just outside of Lerwick. The Museum will give you an insight into the local history and includes a reconstruction of a courtroom used during the time of the Shetland Bus in World War II. Allow around an hour for your visit.
Overall, make sure you plan your time well and choose the most convenient options depending on your interests.