The A83 is a major road in Scotland, running from Tarbet on the western shore of Loch Lomond, where it splits from the A82, to Campbeltown at the sourthern end of the Kintyre peninsula. It is the latter part of the principal route from Glasgow to the towns of southern Argyll.

From Tarbet it goes west across the watershed between Loch Lomond and Loch Long to Arrochar near the head of Loch Long. It then goes round the head of the loch, down the western shore for a short distance, before going westwards, up Glen Croe into the section of road known as the Rest-and-be-Thankful which is the pass through the Arrochar Alps from the shore of Loch Long to that of Loch Fyne.

The section is so named as the climb out of Glen Croe is long and steep at the end, and it was traditional to rest at the top, and be thankful that you had got to the highest point. The current road no longer keeps to the valley floor of Glen Croe but steadily climbs across the southern slopes of The Cobbler to the highest point of the pass. The descent to westward Loch Fyne is through Glen Kinglas, and in this section the main road to Dunoon and the Cowal penisula leaves to the south.

On reaching the shore of Loch Fyne, the main road follows the east shore of the loch northwards to its head and then goes south south west down the western shore through Inveraray and then on to Lochgilphead and Ardrishaig, where it crosses the entrance to the Crinan Canal.

From Ardrishaig the road travels south on to Tarbert, where it crosses over onto the western shore of Kintyre. In the final section it passess through the villages of Kennacraig and Tayinloan before finally crossing back to the east, Firth of Clyde coast just as it arrives in Campbeltown.