Assassin’s Creed: Odyssey—All Underwater Locations And How To Find Them

Assassin’s Creed: Odyssey All Underwater Locations
Achieve the 'Child of Poseidon Trophy'.

What are the Underwater Locations in Assassin's Creed: Odyssey?

One of the most unique aspects of Assassin’s Creed: Odyssey is the enormous open-world map, which is significantly larger than any other game in the franchise so far. Approximately 50% of this map is water, and so players will spend much of the game travelling on the Adrestia. What many players miss, however, is the fact that the sea in Odyssey isn’t just something to travel over—there are 42 underwater locations in the game to be completed.

If players wish to unlock the Assassin’s Creed: Odyssey ‘Child of Poseidon Trophy and Achievement’, all of these locations must be completed and players that aspire towards the platinum trophy will need to collect this trophy first. These underwater locations can provide the players with loot like new armor sets, weapons, gold, ship designs, crews, and more. Once every location has been completed, the trophy or achievement will pop automatically. These locations do not need to be completed in any particular order, and those that aren’t on Kephallonia become accessible as soon as you unlock the Adrestia in Sequence 2 of the story.

Sail aboard The Adrestia in search of underwater treasures.

Players should use Ikaros to mark the underwater treasures and the sharks that are usually found patrolling the area close by. The best way to clear out these locations is by sailing directly to them and then eliminating the sharks with a bow and arrow before diving in. Fighting the sharks is also possible by melee weapons under the water, but this wastes breath and leaves players vulnerable to attack. Kassandra/Alexios will have breath meters that players ought to keep an eye on, indicated by the blue bar above the health meter. While in the water, you can also lunge forward for a speed burst, but lunging in the water will cause the breath meter to deplete faster.

Below, we have listed out all 42 locations in alphabetical order, accompanied by a video indicating where the treasure is hidden in each location. We have also included the objectives to complete in each, what players will find there in terms of crews and ship designs, and if there is a main or side quest pertaining to that location. If there is anything of interest to note about this location, we have mentioned that, too.


1.         Aigisthos Palace

  • 2 Loot Treasure

This particular location in eastern Argolis is extremely deep, and the second treasure chest is not close to the actual palace ruins, making it hard to spot—the above video indicates where you will find it.


2.         Alekto Shipwreck

  • 2 Loot Treasure
  • Lion Figurehead (Figurehead)

The treasure that you are searching for here off the coast of the Isle of Thisvi is not in the shipwreck, but can be found in through the cave entrance next to the sunken ship.


3.         Anaphi Shipwreck

  • 1 Loot Treasure

Quest: Catch and Release

This treasure is best collected while on the small island during the ‘Catch and Release’ quest. It is easy to locate as you don’t have to dive underwater—the treasure chest is instead located on the wrecked ship on the beach.


4.         Ariabignes Shipwreck


  • Find Ainigmata Ostraka
  • 2 Loot Treasure
  • Spartans (Crew Theme)

Quest: Test of Character

This treasure can be acquired while searching for the ‘protective eye’ during the ‘Test of Character’ quest.


5.         Cave of Wealth

  • 1 Loot Treasure

Quest: The Pre-Trial of Endurance

This treasure is easy to locate during the quest ‘The Pre-Trial of Endurance’ if you swim inside the underwater cavern as in the video above.


6.         Dorion Underwater Cave

  • 1 Loot Treasure
  • Followers of Ares - Male (Crew Theme), Followers of Ares - Female (Crew Theme).

This treasure found in southern Lakonia is again made more difficult to find due to the dim lighting and the tricky location of the underwater cave entrance, but once Ikaros has located the chest it shouldn’t be too hard to find.


7.         Hermit's Dive

  • 1 Loot Treasure
  • The Prancing Pegasos (Ship Design)

Quest: Blood in the Water

This treasure is located in the Swordfish’s hideout during ‘Blood in the Water’, in the corner of the room, and can be looted once he is dead.


8.         Islet of Zeus

  • 1 Loot Treasure
  • Quest Item: Prokris's Necklace

Quest: Shark the Vagrant

This treasure can be found very early on in the game while still on Kephallonia during the ‘Shark the Vagrant’ quest, and will probably be the first underwater location you will complete.


9.         Ketos Shipwreck

  • 2 Loot Treasure

Quest: Crewless

This treasure must be looted during the quest ‘Crewless’ and is easy to locate. Following this quest, Kassandra has the option to recruit Gelon to the Adrestia.


10.       Ktesipos's Shipwreck

  • 1 Loot Treasure

This treasure is again easy to locate, and is best done early in the game while still on Kephallonia.


11.       Nereides Monument

  •  2 Loot Treasure

This treasure is easy to find, but swimming from the shore out to the ruins takes some time so it would be wise to sail out by boat. This monument is located off the coast of Mount Koryphum in Argolis.


12.       Olympic Shipwreck

  • 2 Loot Treasure
  • Pegasos Figurehead (Figurehead)

This treasure located off the coast of Elis is underneath the deck of the ship, so make sure to resurface for air if it is hard to locate.


13.       Palace of Amphitrite

  • 3 Loot Treasure
  • Cult of Kosmos (Crew Theme), Scions (Crew Theme)

Quest: The Gods of the Aegean Sea

There are three chests to locate in the palace ruins that are found between Thera and Paros, one of which is a hint about a cult member in the quest-line ‘Gods of the Aegean Sea’. It is probably best to come up for air before searching for the third chest.


14.       Pavlopetri

  • 2 Loot Treasure
  • The Hound of Hades (Ship Design)

The second chest containing the Hound of Hades ship design is tricky to locate, underneath the ruins that can be found off the coast of the Dioskouroi Peninsula in Lakonia.


15.       Persian Remains

  • 2 Loot Treasure
  • Persians (Crew Theme)

These chests are easy to locate and find off the coast of Lokris.


16.       Phaleron Sunken Harbor

  • 1 Loot Treasure
  • Athenians (Crew Theme)

This treasure is extremely easy to find in these ruins in Phaleron Sandy Bay, and should pose no issues.


17.       Phoibean Lagoon

  • 2 Loot Treasure
  • The Satyr (Ship Design)

The Phoibean Lagoon at Salamis is another easy location to complete.


18.       Polydektes Lagoon

  • 1 Loot Treasure

This treasure off the coast of the Pirate Islands can be found by swimming through the darkened underwater cave, but is not hard to locate.


19.       Poseidon's Fury

  • 3 Loot Treasure
  • Eagle Figurehead (Figurehead)

There are again three chests to locate in these ruins north of Patrai in Achaia, so it is best to come up for hair before searching for the third.


20.       Prototype Trireme of Ameinokles

  • 1 Loot Treasure
  • Elite Spartans (Crew Theme)

With just one chest to find in the Korinthian Gulf, this location is relatively easy to complete.


21.       Purrhos the Red

  • 1 Loot Treasure

With just one chest to find in Pandora’s Cove, Malis, this location is relatively easy to complete.


22.       Ruins of Arne

  • 1 Loot Treasure

Quest: Language of the Ancients

In order to open this chest, which is found in Lake Kopais, Boeotia, players will need to swim forward to the skeleton nearby and loot the key to unlock it. This location is part of the ‘Language of the Ancients’ quest but can be completed before this quest opens up.


23.       Ruins of the Sea People

  • 2 Loot Treasure

Skip to 1:37 in the above video to find out where the chests are in between the Silver Islands. One is located underneath some ruins, but they are not hard to locate.


24.       Shark Bay

  • 1 Loot Treasure

Quest: The Elixir

This treasure is found during the ‘Elixir’ quest-line. Skip to 2:20 in the above video to locate the chest in Shark Bay.


25.       Shipwreck

  • 2 Loot Treasure
  • Octopus Figurehead (Figurehead)

No location is specified for the shipwreck simply called ‘Shipwreck’, but this particular shipwreck can be located out at sea north west of the Cradle of Myths.


26.       Shipwreck Cove

  • Cultist Clue
  • 3 Loot Treasure

There are four items to locate in Shipwreck Cove—two treasure chests above ground, one treasure chest underwater, and one cultist clue. The cultist clue is located in the nearby rocks and is tricky to find even when close-by.


27.       Shipwreck of Ajax

  • 2 Loot Treasure
  • Quest Item: Thaletas' Helmet

Quest: Thaletas’ Way

This location can be found during the ‘Thaletas’ Way’ questline. You have the option of lying to Thaletas and saying you couldn’t find the helmet so as to keep it for yourself, or returning it. The second chest in this location is found by swimming through a dark cave next to the shipwreck.


28.       Shipwreck of Dionysos and the Pirate

  • 2 Loot Treasure
  • The Stargazer (Ship Design)

These chests off the coast of Naxos are not hard to find.


29.       Shipwreck of Nestor

  • 2 Loot Treasure
  • Serpent Figurehead (Figurehead)

The two chests located beside this shipwreck off the island of Schiza are easy to find.


30.       Smuggler's Shipwreck

  • 2 Loot Treasure
  • The Chimera (Ship Design)
  • Quest item: Achilles's Dagger

Quest: Blood and Water

This treasure can be found during the Blood and Water quest in Euboea, south of the Forgotten Ruins of Makris.


31.       Stormfall Bay

  • 2 Loot Treasure
  • The Silent Serpent (Ship Design)

These two chests at Stormfall Bay are easy to locate and shouldn’t pose a challenge.


32.       Submerged Minoan Palace

  • 1 Loot Treasure

Quest: We're Treasure Hunters

This treasure can only be located during the quest ‘We’re Treasure Hunters’ which opens up directly after ‘We’re not Thieves’. ‘We’re Treasure Hunters’ can end in three different ways—you can lie to Obelia, you can give her the treasure, or you can kill her.


33.       Sunken Ruins

  • 1 Loot Treasure

Quest: Say That Again!

This treasure can be found during the small side quest ‘Say That Again!’ on the western side of Messara but can also be located without doing the quest. We recommend doing the quest even if purely for the blacksmith’s reward, as it is extremely easy.


34.       Sunken Temple of Aphrodite

  • 1 Loot Treasure

Quest: The Tribute

This treasure is located during the side-quest ‘Tribute’ which opens up at the Site of Iphigenia’s Sacrifice once ‘Chasing Phantoms’ is complete.


35.       Sunken Temple of Demeter

  • 1 Loot Treasure

There is only one chest to find here off the coast of Achaia and so it should not pose a challenge.


36.       Sunken Temple of Eileithyia

  • 2 Loot Treasure

These two chests are located within the ruins off the coast of Messara and so can prove a little harder to locate.


37.       Sunken Wreck of Datis

  • Find Ainigmata Ostraka
  • 2 Loot Treasure

There are three items to find in this location off the south-western coast of Delos but they are all easy to locate and easily accessible.


38.       Underwater Cavern

  • 3 Loot Treasure
  • Quest Item: Triton's Shell of the Titans

Quest: She Who Controls the Seas

This location is part of the side-quest ‘She Who Controls The Seas’ given to you by Xenia after you complete the mission ‘Sacred Vow’. Xenia gives you two maps, one of which is fake—Triton’s Shell is located in Makedonia, as in the above video. The three chests can be found by accessing the underwater cavern and swimming through.


39.       Underwater Cavern

  • 2 Loot Treasure
  • Barbarians (Crew Theme)

Though no location is specified, this cavern refers to one which is found off the coast of Attika.


40.       Underwater Ruins of Dyspontion

  • 2 Loot Treasure

The treasure in these ruins in Elis is very easy to find and shouldn’t pose a challenge.


41.       Vouliagmeni Sinkhole

  • 1 Loot Treasure

This treasure in Attika is again easy to find and shouldn’t pose a challenge.


42.       Wreckage of the Lost Bandit

  • 1 Loot Treasure

This location on Kephallonia is one that you can complete very early in the game, and as such is quite easy to find.


And so, there we have it. All 42 locations. This is a challenging trophy to obtain, in part because some of the locations are hard to find, hard to clear, or even easy to miss. The best way to clear all 42 locations is to simply do them over the course of the game and not all at once, since most of the locations are on opposing sides of the map. Alternatively, players working towards the “Hermes’ Homie” trophy can do them in conjunction. One important final thing to note is that there is no trophy or achievement that can be obtained for finishing the game on a higher difficulty, and so players can complete the game on Easy Mode without worrying that they might miss out.

Good luck on your quest!


You might also be interested in:

Top 10 Assassin’s Creed: Odyssey Best Weapons and How to Get Them

Top 5 AC Odyssey Best Armor

Top 15 Best Assassin’s Creed Games to Play Today


Even after hundreds of hours building up knowledge of every good horror story, all there is to know about RPGs, and the best fantasy has to offer, Katie's most played game is still Stardew Valley.
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