it is hugely popular here in the USA and in the UK.
the reason i posted here is because, this morning in the pouring rain I watched a young couple looking and handling the ball washer thing on the golf course across the street from my house. they saw me watching, and when i went out with the dog, they approached me and told me they were on a geocache. they said there'd probably be about 50 more people come by today. there is a notbook in a plastic baggie attached to the ballwasher, they sign and then move on to the next thing.
i think it sounds like fun, although in aruba, it would be difficult to drag my fat buttocks off the beach and off on this type of scavenger hunt.
disclosure: paul and i participate in scavenger hunts (hidden mickeys) at disney.
this kind of stuff is fun for many!!