This is only semi-relevant. I checked the Wikipedia entry linked to the legend of Levasseur's treasure. Of course, this is Wikipedia, untrustworthy by definition, and the whole article is poorly cited and written. Yet this struck me; if it's true and there is a treasure, I think people have been looking on the wrong continent:
"The treasure chamber is somewhere underground and must be approached carefully, to avoid being flooded. It is protected by the tides, which requires damming to hold them back, and is to be approached from the north."
Two words: Oak Island.
I added a short paragraph on how encrypted messages can sometimes play the role of a treasure map (and also two corresponding examples). I hope the wiki agrees with my extension of definition! In my opinion, encrypted messages that lead to treasure are a variant or subtrope of Treasure Maps rather than another self-standing trope.
Let's just say and leave it at that.
Hello, I was just popping by to look up trope stuff about treasure, wanting to make an authentic parady for myself, and I read this article.
I think it could be worth noting in the "status quo is god" bit that the treasure may also turn out to be a moral lesson, or knowledge that's not directly of value.