Main Walkthrough

Danger Level: 34

Ahh, the open sea. Yes, the oceans of the world are an area you can explore in Octopath Traveler II, and yes, you'll need your own boat to do it. On the Water opens up a bunch of new opportunities for your party, as well as exposing them to new dangers. Ready to take to the high seas?

In order to access On the Water you'll need to commission a boat via one of Partitio's Scent of Commerce quests, specifically the one found in Tropu'hopu. Pay 100,000 leaves for a vessel and you can set sail into the ocean. Once you've made the purchase your ship will replace the ships berthed at the various anchorages around the globe. Boarding at any one of these ports will grant you access to On the Water.


  • Barbed Fish (day only) - Weak to Polearm, Dagger, Bow, Ice - Drop / Steal Energizing Pomegranate (M)
  • Battle-Worn Shark (day only) - see below
  • Dark Manta (night only) - Weak to Bow, Staff, Ice, Lightning - Drop / Steal Refreshing Jam
  • Devious Dolphin - Weak to Sword, Staff, Fire, Dark - Drop / Steal Strengthening Serum
  • Pufferfish - Weak to Polearm, Dagger, Bow, Ice - Drop / Steal Energizing Pomegranate
  • Scourge of the Sea - see below
  • Sea Angel (night only) - Weak to Sword, Dagger, Lightning - Drop / Steal Empowering Lychee
  • Sea Dragon - Weak to Axe, Staff, Fire, Dark - Drop / Steal Healing Grape Bunch
  • Seahorse - Weak to Axe, Staff, Fire, Dark - Drop / Steal Herb of Awakening
  • Swordfish (night only) - Weak to Polearm, Fire, Lightning, Wind - Drop / Steal Refreshing Jam
  • Vagrant Birdian I (day only) - Weak to Sword, Polearm, Fire, Lightning - Drop / Steal Healing Grape
  • Vagrant Birdian II (day only) - Weak to Sword, Polearm, Fire, Lightning - Drop / Steal Dreamy Flower
  • Vagrant Birdian III (day only) - Weak to Sword, Fire, Wind - Drop / Steal Inspiriting Plum
  • Vagrant Birdian IV (day only) - Weak to Polearm, Staff, Fire, Lightning - Drop / Steal Healing Plum (M)

  • East of the Crackridge Harbor: Anchoridge is the Shipwreck of the Empress, a Danger Level 48 dungeon.
  • In the northeast you'll find Frigit Isle, where Osvald began his story. Next to it is Lighthouse Island, a tiny location with a few chests and a Side Story.
  • In the southeast of the map you'll find a whirlpool. See the Scourge of the Sea, below.
  • North of Beasting Bay: Anchorage is Nameless Isle, a Danger Level 38 dungeon.
  • South of Canalbrine is Roque Island. Partitio's final chapter takes place here.

  • North of Canalbrine is a chest containing an Olive of Life (L).
  • Northeast of Canalbrine is a chest containing a Beastly Scarf.
  • West of Canalbrine is a chest containing a Sunken Gold Statue.
  • Follow the Wildlands shoreline to the north of Crackridge Harbor: Anchorage to find chests containing a Platinum Shield and an Invigorating Nut (L). There's a Gold Nugget in a chest at the eastern-most tip of the Wildlands, in the north of the map.
  • East of the Shipwreck of the Empress is a chest containing Strengthening Serum.
  • A chest floating in the northeast of the map, just off the shore of Frigit Isle, contains an EXP Augmentor.
  • South of Frigit Isle, beside a much smaller island, is a chest containing a Dual Leaf.
  • Just south of the New Delsta Harbor: Anchorage, on the east side of the map, is a chest containing 20,000 leaves.
  • Just south of Tropu'hopu is a chest containing an Herb of Serenity.
  • East of the Nameless Isle is a chest containing Reinforcing Jam.
  • Between Nameless Isle and Roque Island is a chest containing a Fortune Wand.
  • Southwest of Roque Island is a chest containing Diffusing Serum.
  • In the southwest corner of the map, off the coast of Hinoeuma, you'll find a chest containing a Double Tomahawk.


There are two boss battles you can wage in On the Water. The first, easier battle is against the Battle-Worn Shark. You'll find it blocking the entrance to the bay between Canalbrine and Conning Creek, in the southwest of the map. The second battle is against the Scourge of the Sea, which is found inside a whirlpool in the southeast of the map. Both are guarding new areas and valuable treasure.

Battle-Worn Shark

Shields: 9
  • Polearm, Dagger, Staff, Fire (first phase)
  • Sword, Dagger, Axe, Lightning (second phase)
Drop: Lost Tribe's Blade
Steal: Nothing

That's a hefty beast. The Battle-Worn Shark is a fairly standard enemy, though it can dish out plenty of damage in a short period of time once it gets going. The Battle-Worn Shark uses the following attacks:
  • A normal melee attack
  • Mandible Crush, a heavy melee attack against one target
  • Gaping Jaws, a heavy melee attack against one target
  • Feeding Frenzy, a melee attack against one target that restores some of the shark's health
  • Devour, which does damage and inflicts Terror on a single target
  • Chomp Ship, which debuffs the party's speed
  • Observe, which changes the shark's weaknesses
  • Feast, a charged attack that inflicts heavy damage to the whole party and restores some of the shark's health
The Battle-Worn Shark starts the fight with two attacks per round, and it will use them to hit one or more characters in your party. Nothing special. Do enough damage to the shark, however, and it will begin pairing up its attacks on a single target, inflicting heavy damage and typically giving one or two characters in your party Terror. Once the Battle-Worn Shark changes its weaknesses it will start to charge up, and if allowed to unleash its attack the shark will use Feast on your whole party. Not ideal.

Per usual, you need to hold back BP at first and use it once Breaking the Battle-Worn Shark becomes a major issue, ie during the second phase of the fight. Keep one character on healing duty while everyone else works on wearing down the shark's shields. Terror can make this difficult, so putting Castti in the party to dispel Terror via her Concoctions can prove quite helpful. Beyond this just use your best multi-hitting attacks that target the Battle-Worn Shark's weaknesses to wear it down. 

In addition to the Lost Tribe's Blade that you receive for defeating the Battle-Worn Shark you'll gain access to the bay it was guarding. In the north of the bay you'll find the Curious Nest, a Danger Level 52 dungeon, and in the west you'll find a chest containing Gimmick Goggles.

Scourge of the Sea

Shields: 12 / 13
  • Sword, Axe, Staff, Fire, Light (first phase)
  • Dagger, Bow, Lightning, Dark (second phase)
  • Polearm, Axe, Bow, Fire, Ice (third phase)
  • Sword, Polearm, Dagger, Axe, Bow, Staff (fourth phase)
  • Sword, Fire, Ice, Lightning (fifth phase)
Drop: Sea Monster's Whisker
Steal: Nothing

Hoo boy, what a pain in the butt. The Scourge of the Sea is an absolute jerk of a boss, and it will spend the entire battle trying to eat your crew. You'll need the ability to target a wide variety of weaknesses to successfully defeat this thing. The Scourge of the Sea uses the following attacks:

  • A normal melee attack
  • Shipwreck, which hits everyone and may inflict Terror
  • Bad Dream, which hits everyone and may put them to Sleep
  • Starboard Straight, which knocks two characters out of the fight temporarily
  • Dark Vortex, which hits everyone for Dark damage and may inflict Blind
  • Pressure, which debuffs the whole party
  • Frigid Flurry, which hits the whole party for Ice damage
  • Whirling Tide, a heavy attack that can Confuse your party members
  • Swallow Prey, a charged attack that removes three characters from the party temporarily
The Scourge of the Sea starts off smacking your characters around, typically with AOE attacks that inflict status ailments (Sleep, Blind, or Terror) or a slap that sends two characters scurrying away. After a while it will try to use Swallow Prey to remove three of your party members, leaving one person to try and Break it to free the rest of the team. The Scourge of the Sea will change weaknesses often.

Get the Scourge of the Sea down to green health and it will change its weaknesses every few turns, hitting your party and then shifting to a charge-up towards Swallow Prey. By this point it will have two attacks per round, and it will use them immediately after coming out of a Break to badly damage your whole party. You'll have a round to Break its shields to prevent it from sucking up your team.

This fight is... obnoxious, to say the least. To survive you're going to need a dedicated Cleric who can clear away wounds in a hurry, and Castti's Concoction abilities are invaluable for sweeping away status ailments. If you can combine both, great - though Castti isn't the best with magic. Still, you can make do (and if you can't, Dohter's Charity is a good alternative, though Castti will have to spend every BP she has on keeping it up). Everyone else in the party, unless they're pumping each other with SP or BP via items, should be focused on attacking.

The emphasis in this battle is on quick restoration of health and chipping away shields. The Scourge of the Sea changes its weaknesses so often that no one character will ever be useful every round, but there are a number of Skills in particular that are great for getting through this fight:
  • HP Thief (Thief)
  • Aggressive Slash (Warrior)
  • Elemental Barrage (Scholar)
  • Precise Shot (Hunter)
On top of these you should consider Skills gained via Ochette's Provoke monsters or Hikari's Learned attacks from townsfolk. Anything that strikes multiple times is useful. It doesn't matter how hard you hit each time, just that you hit. Characters who can go multiple times in one turn (ie Throné, via her Latent Power) are quite valuable for Breaking the Scourge of the Seas. You should also grab the Double Tomahawk, noted in the list of treasures above, as it automatically attacks one extra time.

Once you've successfully Broken the Scourge of the Seas you should preserve BP and only use one point at most to power up attacks. Preferably you'll use attacks that target its current list of weaknesses and just hit hard without needing a bunch of BP. Ochette and Hikari both have Latent Powers that allow for a ton of damage in a short period of time. Once the Scourge of the Sea recovers itself you need to have a decent handful of BP available for healing away damage and continuing the assault on its shields.

If you won, then, well done! That fight is mean, and there's a chance you can run into the thing again once you've beaten it, as a random encounter in On the Water. (Fortunately, you can run from it this time around.)

Aside from the Sea Monster's Whisker, which is a quest item, you'll find a chest floating just beyond the Scourge of the Sea's whirlpool. It contains a Leviathan Greatbow, an excellent weapon for your archers. You'll also find a bunch of other stuff beyond the whirlpool:
  • Follow the shore north of the whirlpool. You'll arrive near New Delsta. There's a chest floating near New Delsta that contains an Inspiriting Plum Basket.
  • East of the whilrpool is The Lost Isle, a Danger Level 45 dungeon.
  • North of The Lost Isle is a chest containing Sublime Ornamental Armor, an excellent piece of equipment.
  • South of The Lost Isle, in the bottom-right corner of the map, is a chest containing a Dual Flower. That was worth the effort.
  • South of the whirlpool is a ??? island. There are a bunch of chests here, five in all, that contain a Skystone, a Dragon's Scarf, and three Herb-of-Grace Buds, (Given the save point I'm guessing this place is important for another reason, but... not sure why just yet.)