Isla Darien: Darien
Found inside the little hut.

That One Floridian's Medical Shack: hippocrates
Found inside That One Floridian's Medical Shack in Gamboa

Gamboa Bar Terminal: raydelron
Found inside of Cosmo's bar.

Panama Farms: fertile
Found in Echo's little bar.

Ronin Outpost: Polyphonic
Found inside of the ronin outpost, which itself is in a disease ridden jungle just off of the Culebra Cut rowboat.

Miraflores Locks: Squirrel
Found inside of Lee's little shack, on the rowboat side.

Ciudad City: Masshallucination
It's the end of the game, and it can be found in a little red building with some cocaine on the table. Not really sure how else to describe it.

These are quite good riddles. Shame on you for cheating!

The grass through the flesh will pass: A spear

When half stained, there is no flame: Rum punch

I want to hide, but my head is outside: Nail

Born in a shell and easy to sell: Pearl

I turn fear into cheer: Adrenal Gland

I still don't get Maman's one. Probably something to do with the survival skills, which I never invest in.