Not the easiest challenge for finding Wherigo's but close. We found our first years ago when looking for every cache type available, (We've now found every type.) That first took effort of three of us to solve. Later we did our first Reverse Wherigo which took a bit of walking in circles and other formations to locate. Wherigo's are a mixture of Mystery and Multi caches making them more challenging than a Traditional.
This challenge won't be hard for most hard core cachers but hopefully will get a few others to solve at least 2 Wherigo's to meet this Challenge.