Strathoykel

River Oykel
Lower Oykel between Brae and Tuiteam house, halfway between Oykel Bridge and Invercassley. The Tutim Burn can just be seen.
Country	Scotland
Basin features
Main source	Ben More Assynt, Sutherland
River mouth	Kyle of Sutherland / Dornoch Firth
Basin size	355 km2 (137 sq mi)

The River Oykel (Scottish Gaelic: Òiceall / Abhainn Òiceall, pronounced [au.ɪɲ ɔːçkʲəɪɫ̪]) is a major river in northern Scotland that is famous for its salmon fishing. It rises on Ben More Assynt, a few miles from Ullapool on the west coast of Scotland, and drains into the North Sea via the Kyle of Sutherland. Traditionally it has marked the boundary between Ross to the south and Sutherland to the north.

The river rises at a height of 1500 feet on the southern side of Ben More Assynt, and flows just over 35 miles. The upper valley is known as Glen Oykel (Gleann Oiceall) and is mostly desolate moorland; the lower valley is known as Strath Oykel (Srath Oiceall). The A837 road runs along the river for most of its length, crossing it just above the junction with the Einig, about 6 miles (9.7 km) west of Rosehall at Oykel Bridge. The eponymous hotel is famous among anglers, who are obliged to stay there when fishing the river.

The River Cassley feeds into the Oykel by Invercassley (Inbhir Charsla), forming the Kyle of Sutherland which is later joined by the River Shin and the River Carron. The Kyle discharges into the North Sea via the Dornoch Firth.

The Oykel was known to the Vikings as the Ekkjal. It served as the boundary between the ancient Pictish province of Cat (Sutherland and Caithness), and the province of Ross, a role it continued until the two were merged into the Highland Region in 1975.

In 1406, the Mackays defeated the Clan MacLeod of Lewis at the Battle of Tuiteam Tarbhach on the north bank near the mouth of the Tutim Burn.