Location from pokemon-horizons by
The 'paradise' Lucius, Rystal, and Gibeon searched a century ago — a hidden biosphere connected to Area Zero where Terapagos can live safely in its Stellar form.
Laqua is not hostile. Laqua is not natural. It is the place Lucius spent his life looking for and where he ultimately died; it is the safe habitat of the Six Heroes; it is the home Terapagos remembers and can be returned to. The Explorers want to mine it for Laquium. The RVT want to protect it. It is the site of the incident where the crew lost Friede for a year — and the final battle of the series.
A sky-scaled cavern larger than any surface city, roofed by a crystal sky of Tera-refracted light. Floating islands of prismatic stone, rivers that flow upward along gravity-inverted channels, forests where the trees glow softly at their hearts. The air is warm, the gravity gentle, the sound of the place like a distant chorus being hummed through water.