Loch Lomond is the largest loch in Scotland, the largest body of fresh water in Britain and probably the most famous after Loch Ness. It is part of the Loch Lomond & the Trossachs National Park, Scotland's first national park. The southern end of the loch is quite flat, but the scenery soon becomes more mountainous and distinctly wild by the time you reach the north end. To the north-east lie the Trossachs with both Loch Katrine and Loch Array.
Towns and Villages
Loch Lomond itself has two routes that run up its shores. The main A82 Glasgow-Inverness trunk road runs up the west bank, and is a good quality single carriageway as far at the village of Tarbet, but then becomes extremely twisty and windy for the northern third of the shore.
The east bank is less accessible, the small villages of Drymen and Balmaha being the two main bases for exploring the Loch’s eastern shores. The road only goes as far as Rowardennan and is barely double track beyond Balmaha: however it does provide access to Ben Lomond as well as several campsites. For anywhere beyond Rowardennan, you will need to either walk or use a boat - some of the cruise companies do call at the key points on the east bank that are north of where the road terminates.
The fastest route to the Loch by far is to follow the M8 motorway through Glasgow city centre, out the other side past Glasgow Airport and exit the motorway at Junction 30 for the Erskine Bridge. This road (the A898) crosses the River Clyde and then joins the A82 westward. From here, follow the signs for Dumbarton, which then lead on to Balloch - signs for "Loch Lomond and the Trossachs National Park" should guide you to the part of the Loch which are of interest. The exception to this if you are coming from the West End of Glasgow, then it is probably quicker to follow the urban part of the A82 through Kelvinside, Anniesland and onward through Clydebank and Old Kilpatrick. Just watch out for the speed cameras along this route!
For a more scenic and slower alternative (particularly if you are going to the eastern side of Loch Lomond), there are a vareity of routes that exit from the north of the city via Kirkintilloch or Bearsden/Milngavie and traverse the picturesque Campsie Fells with many pleasant villages along the way.
From the South
Follow the M74 motorway northbound all the way to its end until it joins the M8 just south of Glasgow city centre. From there follow the route via the Erskine Bridge as described above.
From the North
There are two options - from Central Scotland/Fife, the best route is to take the A811 from Stirling (following the signs to Erskine Bridge). This will eventually bring you out at Drymen and then Balloch. From the North West, follow the A82 southbound from Inverness/Fort William, or from the North East (starting at Perth), follow the A85. Both these routes converge on Crianlarich.
From Edinburgh, take either the main 'Shuttle' service to Glasgow Queen Street (High Level), then go downstairs to Platform 8 to pick up the Balloch train described above. Alternatively, you can take the direct (but slower) train to Platform 8 directly on the Airdrie-Bathgate line that is bound for Helensburgh Central or Milngavie, and change to the Balloch service in exactly the same way - there is probably little difference in overall journey time.
Several trains run daily up the West Highland Line between Glasgow and Oban, Fort William and Mallaig which stop at Tarbet and Ardlui on the north-west shore as well as Crianlarich in the northern part of the park. These leave from the upper level of Glasgow's Queen Street station.
The Caledonian Sleeper from London also runs up here - see the ScotRail website for further details.
The First Group bus service towards Balloch picks up passengers at the bus stop opposite McDonalds at Jamaica Street. A full day unlimited travel ticket costs about 4 pounds.
Several Citylink  buses a day between Glasgow and Campbeltown, Oban or Fort William and the Isle of Skye travel along the western shore (A82) of the Loch. These will stop at all bus stops and laybys north of Balloch, including Luss, Inverbeg, Tarbet and Ardlui. Be advised that prices can be expensive if bought on the bus at the time of travel, for example a single from Balloch Roundabout to Luss can cost £6+.
To enjoy the nature, it is best to go by bike. There's a (relatively!) well-maintained and signposted cycleway from Glasgow to Balloch called National Route 7. A good place to join it is Bells Bridge over the Clyde by the SECC (Scottish Exhibition and Conference Center). It's a fairly flat 20-25 miles.
Buses run along the Loch, but not that frequently (see above). You should check the departure-times first, as timetables are not usually available at the stops. The National Park Authority publishes a timetable of all the buses and ferries  which may be available as a booklet locally.
If you're driving, mind that the road along the northern part of Loch Lomond is pretty narrow for the traffic it has.
Sightseeing trips by boat run from Loch Lomond Shores near Balloch.
There is also a useful passenger ferry between Inverbeg (served by Citylink buses) and Rowardennan (at the foot of Ben Lomond mountain).
The Clachan Inn in Drymen - Scotland's oldest registered licensed premises (1734) - nice pub with good food and friendly atmosphere.
There is a small pub, with outside terrace and nearby pier for boat moorings, on the island of Inchmurrin in the centre of the loch. A ferry is available from Midross, on the A82, to the island. Cameron House Hotel has a marina bar with views over Loch Lomond.