Thun is a town that looks as if someone designed it for a postcard and then forgot to charge for it. The Aare river flows out of the lake through the middle of town in a fast, clear, turquoise channel, past wooden covered bridges and old mills, and above it all stands the castle, a twelfth-century keep with four corner turrets built by the Zähringen dukes, its tall tower visible from many angles. At the foot of the castle hill is the Obere Hauptgasse, a street with raised pavements above the shops, which gives the town centre a quirky, two-level look. With over forty thousand people, Thun has all the services you could want.
Lake Thun itself is long, cold and deep, ringed by steep slopes, with the snowy giants of the Bernese Oberland, the Eiger, Mönch and Jungfrau, visible in the distance on clear days. Schadau Castle, a fanciful nineteenth-century château on the shore, sits in a park that is lovely in the evening. Paddle steamers still cross the lake, and you can often see their wake from the road. Thun is also a long-standing army town, with the Swiss military's training facilities, so you may see soldiers in town.
The ride to Lauterbrunnen follows the lake past Spiez and Interlaken, with the water on one side and the mountains rising on the other. It is a scenic road, not a hard one, and the bends are gentle, with villages, vineyards and orchards beside it. Traffic can be heavy in summer, particularly near Interlaken, so leave early if you want the view without the queue. Be aware that speed limits are enforced firmly in Switzerland, with plenty of cameras, and that a fine can be expensive, so keep it relaxed.
Before you go, fill the tank and have a coffee in the old town. Spring brings blossom around the lake and snow-capped mountains behind it, while autumn is clear and crisp. Winter fog can sit on the water for days. In the right light, with the alps pink at the end of the lake, Thun justifies its reputation.