Purpose / Function
The Sunhaven Gym is used as an inside-out aquarium, and thus as a giant tourist attraction. It is also used as an unofficial outpost for the coast guard and the corpse divers squad, lead by Leader Valai.
In addition to that, it is used as a Pokémon gym (duh), lead by Valai as well, who specialized in Water Type Pokémon.
The dome is a half-sphere of glass, built on a solid round block of dark concrete. The radius of the sphere - and thus the height of the dome - is roughly 20 meters. The ground is covered in black pool mats.
Below the pool mats, there are a total of 300 air holes, connected to a giant underground ventilation system. The tunnels of the ventilation system are accessible through a secret and locked trap door, which is covered by a bath mat as well. The tunnels are just broad enough for a facility manager to walk through them, so they can refill the Oxigen bottles and empty the Carbon.
A concrete tunnel on the Southern side goes straight out from the sphere, where it is close to the ground.It has an electric doorway on the bottom, which can be connected to a U-boat.
Near the walls, there are a couple of metal signs, describing the Pokémon and plants that can be seen from inside the dome.
Across the entire dome, there are long tables with benches attached to the ground. Only in the middle, there is an area whithout any tables. Instead, there are benches around that central area, placed like in an arena. Here, the gym battles take place.