Fountain of Youth: where is it? (Likely severe spoilers)

[Scourge]

I've basically scoured every inch of the Mexico map and the Hispaniola map and not found it. I found El Dorado pretty easily actually, but I have no idea where the fountain is.

Little help?

EDIT: I mean I uncovered as much of the maps as seem uncoverable, I don't think there's anywhere left to explore. But if I had a hint as to where to search, it would hlep.

[Nova]

Far North West

[Jack Dandy]

Have you found the home of the doctor who knows Anacaona? It's in a path to the north-west of his house.

[Scourge]

If you'll pardon the expression, OMG, I can't believe I missed ALL of that stuff past the mountain range to the west of the fortress. Ay, Dios Mio.

[~Finzi~]

It's in a secluded rainforest/mountainous area in the North West, PAST the fortress.