Hiking is Germany's favorite outdoor activity, with 34 million Germans lacing up their boots each year, according to estimates. Each September, the German Mountaineering and Hiking Association sponsors a national Hiking Day, which serves as an annual reunion for German hiking aficionados and gives members in the country's many local clubs a chance to get together at one big event.

The Mountaineering and Hiking Association is charged with grooming and marking some 190,000 kilometers (118,000 miles) of trails, many of which traverse mountainous landscapes. The association can also provide information on the many Hütten, or huts, that lie along the trails and provide shelter for hikers.

There are 78 officially designated trails and trail networks that the association has recognized, but four main hiking regions stand out as Germany's most popular and most impressive. (Americans could compare these to hiking the Appalachian or Rocky Mountain trails, while

Brits could keep the Peak District or the Scottish Highlands in mind.)

As the crisp autumn weather begins in Germany, now may be the time to embark on one of the following trails:

Maximiliansweg and the Bavarian Forest

First of the four is the Maximiliansweg, which follows the route in the Bavarian Alps that King Maximilian II took when he crossed the mountain range in the company of a large entourage (which included writers to document the tour).

The route goes from the Allgäu region to lake Königsee, and takes about 14 days. The strenuous trip encompasses some of the country's most famous peaks, beautiful Alpine landscapes and views of the Bavarian Alps.

The second route leads through the Bavarian Forest, between the Danube and the Czech and Austrian borders. Known as Europe's Green Roof, the Bavarian Forest is central Europe's largest closed woodland area. The region once housed more than 60 glass works, a handful of which still exist today, and the "Gläserner Steig" (Glass Ascent) trail takes hikers right through this region -- which leads past glass works and traditional manufacturing villages -- in a walk that takes about six days.

Black Forest and Sauerland

The network of hiking trails in the Black Forest consists of more than 23,000 kilometers of signposted hiking trails which criss-cross the most beautiful areas of the region. The most famous of these are the 16 long-distance hiking routes on the "Westweg" route.

The route crosses the European watershed, between the Rhine and Danube Rivers. This part of the trail offers superb views across the deep valleys of the Western Black Forest and the flat high-lying valleys in the east.

Finally, the Rothaarsteig in the eastern Sauerland low-mountain region (the highest peak is some 840 meters in altitude) is less touristy and offers more nature and less culture than the others. The path that leads through the area is rough and sometimes a bit wild.

Crystal clear waters flow, having been filtered by numerous layers of slate, originating from the rivers Ruhr, Eder, Lenne, Dill, Lahn and Sieg. The region offers an abundance of routes and paths that allow visitors to relax while discovering nature with all of their senses.