The Wish Rock Garden is an area nearly a mile long along the North Shore. People have for years made small stacks of rocks that are meant to protect this island from storms and other evils. There are probably hundreds of thousands of stacks of rocks along the road.
The location will require that you have some form of transportation. The tours go by here but don't stop long enough for you to find this cache. I rated it difficult because you will need a vehicle and the site itself is so full of rocks that you will probably have to search pretty hard to find it.
Initially I placed several Aruban souveniers in the cache that includes postcards, 2 key rings, 1 bottle opener, a log book & pen, and The Stamp Collector Travel Bug.