Batman flys above the tide Wherigo Cache

In order to find this Reverse Cache you need to download a Wherigo cartridge made by -Waldmeister-

Every time you ask it, the cartridge will tell you your distance from the cache, but not the direction.
Based on this information you should eventually be able to deduce the final location.
Once you get within about 20 metres from the cache, the cartridge will give you exact coordinates.