Final Fantasy III/Nepto Temple

Healing Copse
Now that you're out of the nest, it is a good idea to save. Also, equip one of your characters with the Mini spell and walk to the forest to the southwest. Besides a Gnom there are 3 different Springs there. One to revives any deads, one to restore HP/MP and one to cure all status ailments. There, you will receive another Mini spell from a Gnom. Use the Mini spell on all characters. It's probably a good idea to change your physical-based jobs to magic-based jobs, since as Gnomes your physical attacks won't work well. Walk south to enter Tozus.

Tozus
Once in Tozus, walk and enter the house in the northwest corner and talk to the doctor. Give him the antidote and the doctor will open a secret passage as a thank for your help. But before going down check the room for 4 treasure (Mythril Bracers, Fire Staff, Spell Fira and Spell Cura). You may also need to buy some spells for your mages.

Tozus Tunnel
Open the two chests (2x Phoenix Down) and go down the stairs. Walk through the passageway until you are on the world map. Save, then enter Vikings Cove northwest of Tozus Tunnel.