Achagoyle Bay is coastal embayment, on a chord of 0.75 miles, on a 114° orientation, on the western coast of the longest sea loch in Scotland, Loch Fyne located in Argyll and Bute, on the west coast of Scotland. Achagoyle Bay is directly northwest of on a NNE orientation, which forms a rightward hook, and opens into the with a NE orientation, also with a rightward hook, directly south. The three bays constitute the western edge of the which is bounded by the islands An Oitir and Eilean Aoghainn directly to the east of Brainport Bay.