Car:

Exit Autobahn Interlaken Wilderswil. Look out for the Tennis & Squash Center which is 300 meters to the left.
For GPS: Mittelweg 5, 3812 Wilderswil

Train:

Get a ticket to Wilderswil. Train rolls along Tennis into Wilderswil station - Walk 1 Min. back to the Tennis  

Free Pick-up service:

At train station Interlaken OST or any hotel in Interlaken