Final Fantasy I & II: Dawn of Souls/Soul of Rebirth/Unknown Cave

Don't worry too much about the chests, the enemies here are so strong you'd better find friends as soon as possible. And, since the fourth party member is met on second-last floor, you'd better continue to the safe area Machanon (it reminds of "Safe Area Gorazde" in the Bosnia war). Once you got there, rested and done a little bit of shopping, get back to collect all the chests, and raise your characters, too.

Enemy roster
Exploit the weaknesses of the enemies to beat them quickly. Luckily, many are undead (absorb Death, weak against Holy), so Minwu's Cure and Life spells will come in handy to attack.

Still, it is quite necessary to cast Blink and/or Protect at the begining of most combats, especially when your party is smaller than four.

All enemies are very strong. In the following table, monsters are sorted according to the in-game bestiary, and all the information comes from there.

Only few of their attributes are listed, the most useful to fight them, in order to keep the table easily readable. For a full bestiary check the Bestiary page.
 * Rank summarizes well how dangerous the monster is;
 * HP and weakness are essential about the monster endurance;
 * MP is useful for Minwu's Swap spell, in case you want to replenish his MP without using ether;
 * Treasures include some useful items that are only made available by defeating the enemies.

Team of two: Minwu and Scott

 * Boss: Dark Knight: What? you start the game with a boss? And it's not Batman either! If you're lucky, the boss can drop a Yoichi's Bow, that allows to cast Berserk L3.
 * Floor 1: To get to the next level, walk straight to the left.
 * Floor 2: To find the next stairs, you have to follow a winging path: first up, then left and down all the way (it may be worth collecting the Ancient Sword in the chest at the bottom), then left again and up.

But wait! An ally, Josef, is there and he's not alone.

Team of three: Josef

 * Boss 2: Zombie Borghen: Did you think you beat the dungeon boss already? Think again! Zombie Borghen is an undead, so he's weak against Scott's Fire spells and Minwu's Cure and Life.
 * Floor 3: Follow the winding path around and under the waterfall; the exit to the next level is the very last door in the lower-left corner. There is a secret magic shop under the waterfall bottom, but you probably won't have enough money to buy all the spells now.
 * Floor 4: Nice green grass fields, a clear water river and... more deadly enemies! To find the exit quickly, just walk straight left from where you arrived.
 * Floor 5: Read the inscription near the entrance, then walk following the ledge.

Team of four: Ricard

 * Boss 3: Roundworm: You can actually skip this one, but if you do so, you will also miss your strongest ally, Ricard the Dragoon.
 * Floor 6: This is the last floor, just follow the corridor until you get to the portal, and you can finally relax.

From the chests
Rest in Machanon, then get back to the Unknown Passage to collect all the chests.
 * Start: 10 ethers, 5 phoenix downs
 * Floor 1: elixir, ether
 * Floor 2: ancient sword (inflicts "curse"), thief's gloves (increase speed), hellfire
 * Floor 3: silver cuirass, secret magic shop (Berserk, Haste, Holy, Flare)
 * Floor 4: hi-potion, Aura tome, demon spear, golden shield, eye drops
 * Floor 5: ether, protect ring, h-potion
 * Floor 6: (portal to Machanon)