From Munich on the A95 direction Garmisch-Partenkirchen. The highway ends just before Garmisch-Partenkirchen and turns into the main road B2. You reach the Partnachklamm, if you follow the B2 direction Mittenwald (Mittenwalder road) and at the exit of Garmisch in the direction of Skistadion turn right (Wildenauer road). After a short while, you will arrive at the Olympic Ski Stadium, where ample parking is available for a fee.
With the blue Eibsee bus (commutes between Eibsee and Garmisch-Partenkirchen) you go to the bus stop at the train station in Garmisch-Partenkirchen. Either you then use the Garmisch-Partenkirchen local bus (line 1 and 2) or you walk on foot in about 25 minutes. There is one nice to the starting point Skistadion just along the railway line Grainau - Garmisch-Partenkirchen.
By cog railway of the Bavarian Zugspitzbahn BZB (commutes between Zugspitze and Garmisch-Partenkirchen): From the Zugspitze railway station, there is a nice walk along the Partnach shore to the ski stadium. A special experience is it to ride a horse-drawn carriage from the ski stadium on a flat road into the Wildenau. This will take you directly to the gorge entrance.