Can't realy remember the exact location because the forgotten continent is pretty large, however I did find some ifo on it for you concerning a more exact location....

Dead Pepper Treasure 3
Mountain crack near Oilvert

Meme advice (There's a forest nearby the crack in the mountain. The crack is somewhere a little northwest of Oeilvert. The crack is on the mountain that faces north.

Below is an image of the world map - you'll be able to spot the treasure you need labelled as a red circle. I'm pretty sure that it is the one furthest north on the forgotten continent, I seem to remember it being there. k!