Scotland's longest loch abounds with islands and crannogs. Many of the islands are, or have in the past, been inhabited; there are two castles and the remains of a chapel on the islands.
Inistrynich, Eilean na Maodail, Eilean Dubh and Liever Island are all promontories as opposed to islands despite their names. this loch's water levels have fluctuated so some of them may have been islands in recent history, as Kilchurn Castle's promontory once was.
Islands located in Loch Lomond [1] There are said to be sixty islands in the loch - including Inchmurrin, the largest fresh water island anywhere in the British Isles, including Ireland.[2]
Here are a few images for reference. Further images can be seen on Wikimedia Commons at Category:Lochs of Scotland and further sub categories listed there.