Bubbly Basin treasure maps

Find the six decorative balls for the Mermaid’s Gym habitat.

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Walkthrough

In Bubbly Basin, look for the six maps alongside the daily hidden relics and CDs. The maps depict the old Cerulean City and point to decorative balls; take a Search Pokémon and Dowsing Machine to narrow down the hidden rooms.
Use the landmark table as a route rather than digging everywhere: the Great Ball is near the Center’s waterwheel, the Dive Ball beside the old gym, and the Net Ball in the northern cave mines. The other rooms are near the windmill pagoda, Bill’s green-roofed house and the entry gate.
Keep all six finds for the Mermaid’s Gym habitat. After obtaining an item, its recipe can appear later among daily shop specials. The source labels the final section map 6 but repeats map 5 in its paragraph; the Quick Ball location is reported under that sixth heading.

Map	Landmark
1 · Great Ball	Behind the building west of the Pokémon Center, near the waterwheel; break the eastern wall.
2 · Heal Ball	West of the pagoda with a windmill above the waterline; dig down.
3 · Dive Ball	Break through Star-spotted rocks beside the former gym.
4 · Net Ball	In Frillish’s northern cave, east of the giant crystal in the mines.
5 · Lure Ball	West of Bill’s green-roofed house, dig by the lone tall grass.
6 · Quick Ball	North of the entry gate, break Star-spotted rocks beside the ruined building.

Situation	What to check
The landmark is visible but the room is not	Search with the Dowsing Machine and break through the specified wall or rock.
A decorative ball is needed again	After the first find, check daily shop specials for its recipe.

The source’s sixth heading identifies Quick Ball as map 6 although its following sentence repeats “map 5”; treat the number as a source inconsistency.