150m north of the giant's cauldron (hiidenkirnu). The container is a 18x18x6cm plastic box.
I put the detailed description of the site in the hints/spoilers info.
Be sure to check out the giant's cauldron, it's one of the smallest I have seen, but nice still.
Haqre na byq cnegyl snyyra nobhg 2.5z gnyy whavcre va n pyrsg ng gur fvqr bs ebpx.