Unst is the most northerly inhabited island in the UK, though is reachable from mainland Scotland within 3 hours.
Getting To Shetland
Shetland can be reached by plane or boat. FlyBe operate regular flights to Shetland from Aberdeen, Glasgow and Edinburgh. Flights are short and take around an hour to arrive. Northlink operate the ferry service to Shetland and have sailings most evenings. The boat journey takes 12 hours (overnight) and allows you to take your car/bike with you.
Getting To Unst
If you arrive by plane, you will be in Sumburgh, the southernmost tip of Shetland. The A970 road will take you northwards. Arriving from Lerwick, this same road will take you as far as Voe. At which point take the A968 (North Isles) and stay with this road (via 2 inter island ferries) until you reach Unst.
Note: You only need pay on the inter island ferries when travelling northwards.