>The treasure has been around for so long, and there have been so many attempts at it, I figure there is no way that it has not been discovered yet

This one has been going on for even longer: https://en.wikipedia.org/wiki/On_the_Trail_of_the_Golden_Owl

And here we're certain it hasn't been found since only a token has been buried, the real golden owl will be given in exchange of it.