The Karwendel mountains are a range of limestone peaks and ridges running along the northern border of the Austrian Tyrol and the southern border of Bavaria.
Both the Bavarian and Tyrolean sides of the border are protected nature reserves and, with more than 900km², form one of the largest protected areas in the eastern part of the Alps.
The Tyrolean side of the nature reserve is much larger and more vigorously protected - the Naturpark designation is one step below being a national park.
On the Bavarian side, which runs from the top of the northernmost chain through to the foothills south of the Walchensee and Sylvensteinsee, the protected area is a Naturschutzgebiet - a slightly lower level of protection which reflects the increased population on the northern edges of the reserve.
The most developed and closest village to the Karwendel area in Bavaria is Mittenwald. The mountain range to the east of the village forms the western edge of the Bavarian nature reserve and is served by the Karwendelbahn cable car, the second-highest in Germany.
A popular excursion from Mittenwald by mountain bike is to visit the source of the river Isar in the Austrian part of the park. The Isar flows into the Sylvensteinsee (a reservoir) and then north through Lenggries to Munich and eventually into the Danube.
Alternatively walkers can taken marked walking paths from Mittenwald to the Krinner-Kofler hut or up to the Soiern lakes below the peaks of the same name.
A shorter route for the German Alpine Road runs directly from Wallgau along a toll road to Vorderriss and then on a normal road to the Sylvensteinsee and up the Isar valley to Lenggries. (The traditional Alpine Road route runs via Kochel am See on country roads to Bad Tölz.)
A popular route into the park runs from the Vorderriss junction (south of Jachenau on the toll road) into the Austrian part of the park and up to Hinterriss or eventually to the Grosser Ahornboden and the Eng pastures.
In the summertime (mid-June to mid-October) a daily bus runs on this route between Lenggries and the Engalm (with stops in between). Note that the Bayern Ticket regional rail/bus ticket is not valid on this bus as it operates in Austrian territory as well.
However the regional bus service offers a Karwendel Ticket which allows return travel on BOB (the regional train service between Munich and Lenggries) and the Engalm bus within a period of 5 days.