Danger Level: 20
Location: Eastern Sunshade Sands, northwest corner of the map
One of the earlier dungeons you can run across in Octopath Traveler, the Whistling Cavern is a good spot for players to get used to stronger enemies after completing a few Chapter 1s. The enemies are tough without being impossible, and there's no frustrating boss that will bar your path. It's also not very long, and the treasures inside are worth grabbing (all the more if you bring Therion along).
There's no free ride through a dungeon, of course, so you'll be facing the following foes in the Whistling Cavern:
- Skull Roller - Weak to Polearm, Ice, and Dark. Can hit somewhat hard, but they're pretty weak compared to everything else in Whistling Cavern.
- Dark Roller - Weak to Dagger and Lightning. Hits much harder than the Skull Roller and has few weaknesses, but - mercifully - it only takes one hit to stun. Knock it out of commission and leave it until last, as these things have a lot of health.
- Dire Army Ant - Weak to Sword, Dagger, and Axe.
- Antagonistic Ant - Weak to Dagger and Staff. Uses Jaws of Darkness to blind a single target. Annoying thanks to their few weaknesses, though they don't have enough health to hold up against other attacks. Cyrus can help against crowds of these things with any of his spells.
- Killer Bug - Weak to Sword, Axe, and Dark. Uses Sharpening Claw to buff the whole group and several melee Skills that can inflict serious pain on your party. Olberic and Primrose are good at dealing with them quickly.
- Slayer Bug - Weak to Sword and Axe. Similar to the Killer Bug, but hits much, much harder, and has a lot more health. Stun them and take out weaker surrounding foes first.
- Giant Scorpion - Weak to Polearm, Ice, and Wind.
- River Fly - Weak to Polearm, Bow, Ice, and Wind. Hits hard and is fast, but stuns very easily. Tressa and Cyrus can wipe a whole group of them.
- Horse Fly - Weak to Polearm, Bow, Ice, and Wind. Slightly tougher version of the River Fly, but the same strategy applies. Cyrus will have an easier time since he can reliably hit twice in one go.
Trek over to the save point near the entrance. You're immediately at an intersection. Take the western path and follow it until it veers north. You'll find a purple chest containing 6,000 leaves. Heading northeast from here will link you up with a path from the previous intersection. Follow it north to reach another intersection.
Take the western path from the northernmost intersection and it will take you to an open area with a chest containing a Fire Soulstone (M). Take the northern path from this intersection and you'll find a chest containing an Inspiriting Plum (M) through the obscuring rocks on your right. The eastern path leads to a dead end, so, meh.
One last thing. Use the eastern paths to trek back to the save point. There's a final path to the north that you skipped earlier. Follow it until it splits to the north and the south. Go north and you'll find an Olive of Life (M) nearby. Go south and you can find a path that wraps around on itself and leads you to a chest below, containing a Heavy Bow. This is the longer path, but once you have the bow you've collected everything in Whistling Cavern, so feel free to warp out.