Aqua Garden is a vibrant, oceanic world with gigantic bubbles and fish flying through the air. This level's main gimmick is its Fountains, which can propel NiGHTS or Helen with a current of water when activated. This level's boss is Girania and its hidden ideya is Helen's White Ideya.
Helen climbs the chain on NiGHTS' cage in order to dualize with them and chase after the Goodles riding peacock-like birds in pink, blue, and green in order to take their keys and unlock the three NiGHTS cages. In this mission, the player can paraloop Nightopians and Nightmarens into the My Dream world. Once all of the cages have been opened, the player will be sent to battle Girania for the first time.
Owl challenges Helen and NiGHTS to push the giant bubbles into the center Aqua Sphere and make it bigger. When the time runs out, the mission ends.
Octopaw makes his first appearance to Helen, whom NiGHTS challenges to make a link of 25 with the rings and blue chips Octopaw releases. The player gets five chances to make the necessary links to pass. Links of four or under, however, do not count as a fail.
Wizeman creates a tornado and sends Helen flying down into a deep ocean trench. In this mission, the player only plays as Helen and attempts to reach NiGHTS at the top of the trench before the Awakers come to wake Helen up and cause a Night Over. The mission ends when Helen successfully reaches NiGHTS.
This is the final mission of Aqua Garden, where the player must once again battle Girania, who is noticeably bigger than normal. Once again, NiGHTS must ram into Girania to break him up into multicolored spheres, then use a paraloop to suck in as many spheres as possible in the limited amount of time before he reassembles. Sometimes, Girania will burrow into the ground and the player must wait until he resurfaces. If NiGHTS flies into Girania's mouth, they will be swallowed and take five seconds' worth of damage. Once he is defeated, the player gains the White Ideya of Purity, the Dolphin Persona, and access to the second world, Crystal Castle.
Sega Superstars Tennis
The court is located inside a tholos marble temple with a shallow water pool. The temple previously appeared in the second lap of the Aqua Garden level from NiGHTS: Journey of Dreams. This tennis court is also used for the Puyo Puyo minigame.
The Aqua Garden court is unlocked by clearing the first mission in the world of NiGHTS into Dreams from Superstar Mode.