Bubbly Basin packs a surprising amount of secrets into its underwater world, and Treasure Maps are one of the more rewarding puzzles to solve in Pokémon Pokopia. There are six of them scattered across the region, each pointing you toward a special Pokéball that sits on a pedestal. 
Collect all six and you can spawn 
Starmie, the signature Pokémon of Cerulean City Gym Leader Misty. Here's every location and solution.
How do Treasure Maps work in Pokémon Pokopia?
Treasure Maps are not sitting out in the open waiting for you. They spawn as hidden loot inside blocks that glow with a yellow aura, and you grab them by using Rock Smash on those blocks. The catch is that spawns are not guaranteed. The same blocks can also drop Mew mural pieces, relics, fossils, or other collectibles, so you may need to crack open several before a map shows up.
Hidden loot blocks glow yellowHere's the thing: you do not actually need the maps themselves to collect the rewards. Every special Pokéball can be found through direct exploration at any time. The maps just point the way. If you are short on time, there is also the photo and 3D Printer method: take a photo of an item you already own, head to a friend's game or a Cloud Island, and print a copy.
All 6 Treasure Map solutions in Bubbly Basin
Each map leads to a specific Pokéball hidden somewhere in Bubbly Basin. Place all six on the pedestals in front of the Cerulean City gym building to trigger Starmie's spawn. The table below has every solution in one place.
Pedestal placement for StarmieWhat's the fastest way to all six Pokéballs?
If you are running through Bubbly Basin efficiently, tackle the maps in order of proximity rather than number. Maps 3 and 6 are the simplest to grab since both locations are tied to obvious landmark buildings (the gym and the Southern Gate house). Maps 1 and 4 involve breaking specific hidden walls or rocks, so bring plenty of tools before heading in.
Map 5 is the one that trips people up most often. The 
Tall Grass patch north of Bill's House looks like background scenery, not a treasure location. Dig straight down when you find it.
Printer shortcut works well if you have already found one Pokéball and need duplicates, but each pedestal requires a distinct ball type. You cannot print six copies of the same one.
Dig here for the Lure BallWhy bother with Treasure Maps at all?
Spawning Starmie is the main payoff, and it is worth the effort if you are pushing to complete your Pokédex in Bubbly Basin. Starmie does not appear through standard habitat exploration, so the pedestal method is the only reliable route. For a full picture of every Pokémon available in the DLC, the Pokémon Pokopia Bubbly Basin all Pokémon and specialties guide covers every species alongside their Specialty lists.
Beyond Starmie, the treasure hunt itself doubles as a reason to poke around corners of Bubbly Basin you might otherwise skip. Several of the hidden rooms sit near other secrets and resources, so a focused treasure run tends to pay off in more ways than one.
For everything else the expansion has to offer, the full Pokémon Pokopia strategy guides collection covers habitats, new Pokémon spawns, habitat temperature mechanics, and more.