Naboo
My favorite Star Wars setting
Naboo was a geologically unique world in the galaxy. A plasmic molten outer core surrounded an inner core, believed to be composed primarily of a nickel-iron alloy, with very small amounts of some other elements. These elements were found in abundance in other chemical compositions in the galaxy, but it is the unique properties of the plasma which interested astrophysicists, plasma which the two primary civilizations harnessed to supply clean and efficient energy highly valued throughout the galaxy.
The plasmic magma "seethes and bubbles" from the center of the planet carving labyrinths of winding tunnels and caverns similar to lava tubes of traditional magma flows. Much of these abyssal labyrinths were submerged in great underground oceans, which were home to immense aquatic animals and creatures that were never seen on the surface. Animals such as the colo claw fish, opee sea killer, sando aqua moster,and others inhabited this underworld realm. Gungans dominated these "underwaterways," using them as a highway of sorts between their surface Holy Places and their underwater cities. The Gungans also used these tunnels for trading between Bubble cities.
Plasmic eruptions found their way to the porous crust of the planet, affecting geographic features there such as mountain chains and plate tectonics.
The surface of Naboo was covered by dense swamps, rolling grass plains, seas and verdant hills. The largest mountain chain, the Gallo Mountains, bisected the largest continent and divided the great grass plains of the north from the Lianorm Swamp and bayous in the south. South of the Lianorm Swamp was the great Paonga Sea, where at the bottom lay the Gungan city of Otoh Gunga. The Lake Country was an area known for its natural beauty, and was home to many vacation estates.