Back home there is a tradition for "Unknown caches" and this has also been a sucess on Gran Canaria.
These caches are not regular plastic boxes, but they can be anything you can imagine....... There will always be a logpaper inside, but you will have to bring your own pencil. A log with a photo of the container will be deleted immediately! This has become a serie and we will be very pleased if you log DNF if you don't find it, but look at the Difficulty-rating before you say it isn't there.... This is not a cache that everybody will find, but is more like a challenge for those who have been into the game for some time.
And please: Try to replace it the same way you found it. Good Luck and Happy Hunting 