To get to the Shetland Islands, you can either drive or take a train followed by a ferry ride.
If driving from Aberdeen, take the A96 past Inverurie and onto the A952. Follow the A952 through Mintlaw and Fraserburgh until you reach Peterhead. From Peterhead, take the A90 north until you reach the ferry terminal at Aberdeen. Board the ferry to Shetland Islands.
If taking the train from Edinburgh, Glasgow, or Aberdeen, take the train to Thurso or Scrabster and board the ferry to Shetland Islands. Alternatively, you can take the train to Aberdeen and follow the driving directions above.
It is also possible to fly to Shetland Islands from Aberdeen, Edinburgh, Glasgow, or Inverness.
Overall, the best option depends on your starting location, budget, and preferred mode of transportation.