The essential Loch Lomond experience is getting out on the water. Cruises of one to two hours leave from Balloch, at the southern tip, and from the pier at Luss; they are inexpensive, run for most of the year and are the best way to see the islands and the mountains at the head of the loch. In the Trossachs, the Loch Katrine steamship is a piece of living history.
If you are based in a city, a day tour solves the transport puzzle. From Glasgow the loch is under an hour away; from Edinburgh, tours typically combine it with Stirling Castle and the Kelpies. See also Stirling tours and, for trips continuing north, Glencoe.
