This is a Reverse Wherigo.
The Reverse Cache Box
You have a ‘Reverse Cache Box’ which does not display coordinates, but only the distance to the final/geocache.
In this case, the Reverse Cache Box is your GPS device.
Your task is now to check the distance as infrequently as possible and to find the geocache using only this distance information.
You need this Wherigo Cartrige:
http://www.wherigo.com/cartridge/details.aspx?CGUID=dcdcd2ff-c171-4487-93bc-678f6d03ac4f
At the beginning you have to type in this Codes:
403188
884350
148864
Enjoy;-)