Altar of the Tidemother is a shrine to the Astral Leviathan situated amid the city of Altissia in Final Fantasy XV. It appears in cut scenes in Final Fantasy XV and is a playable location in Final Fantasy XV: Episode Ignis. The structure is so ancient its original purpose has become unknown, but the government safeguards the shrine in wait for the day the Oracle will commune with the Tidemother.
Built of stone, the altar extends into the Celluna Cascades, connected to the city via a bridge. Two flights of stairs lead to the top that has two poles posted around the altar, four colossal vases of purple flowers and a large stone circle. Part of the structure is damaged, with a part of the circle and the top of a pole missing.
The almanac entry is found northeast from Leville hotel in Altissia, on a marble bench, in the Windows and Royal Editions.
- Ancient religious structure jutting out into the Celluna Cascades. The government has apparently taken a vested interest in safeguarding the shrine, forbidding all unauthorized access.
- While the shrine is now widely known as a place for showing reverence for the sea goddess Leviathan, its history is shrouded in mystery. The bollard-like poles posted around the altar suggest this spot may have once been used for mooring boats. Others postulate it may have been an astronomical observation point from which seafarers studied the stars to strengthen their celestial navigation.
The structure's age implies it may hail from the age when the human civilization, known as Solheim, co-existed with the gods. Though now a religious structure to revere the sea goddess, its original purpose has been lost to history. Solheim crumbled in the wake of the War of the Astrals, and the gods fell asleep, Leviathan slumbering beneath the Celluna Cascades in the altar's vicinity. The city that formed in this area became to revere her as its patron goddess, and the altar has been used for religious purposes to her honor. In current times access to the altar is restricted, as the government of Accordo safeguards it in wait for the prophesied time when the True King will arrive and the Oracle of his time will commune with the gods.
Lunafreya Nox Fleuret believes Prince Noctis of Lucis has been chosen by the Crystal and begins her pilgrimage to rouse the Astrals from their 2,000-year-old slumber. She meets with First Secretary Camelia Claustra, asking passage to the altar to rouse Leviathan. Claustra is hesitant, as the gods' Revelations leave great destruction in their wake. She invites Noctis to meet her in person, and the latter convinces Claustra to let Lunafreya perform the ritual. Lunafreya gives a speech to the masses, publicizing her intentions, and the Trident of the Oracle in hand ascends the altar while Noctis lies in wait. All parties know that the Niflheim Empire will attack as soon as Leviathan appears, intent on killing her before she can forge a covenant with Noctis.
Leviathan emerges from the cascades at Lunafreya's beckoning, furious at being addressed by a mere mortal. She intimidates Lunafreya, threatening to devour the people of Eos. Lunafreya repels the sea goddess's aggression with the trident and gets her to agree to test Noctis. Imperial air force arrives to harpoon Leviathan, who shakes off the wires and crashes the airships. Noctis fights his way through imperial soldiers and hitches a ride with his friend Prompto Argentum on an imperial magitek harpoon. Noctis ends up on Leviathan's eye level and asks for her power, enraging her further. She envelops the area in a whirlpool with city structure's caught up in it.
During Noctis and Leviathan's battle Ardyn Izunia approaches Lunafreya on the altar and stabs her in the stomach, knowing Noctis would witness it. When she grasps his sleeve her powers of healing activate, but he recoils from her touch and walks away. The dying Lunafreya calls upon the powers of the kings of Lucis to empower Noctis who enters a sustained mode of Armiger, triumphing over Leviathan. His power spent, Noctis's unconscious body washes up to the altar where Lunafreya heals him. Titan, with whom Noctis had forged a covenant earlier, appears outside the altar and raises an earthen wall to block Leviathan. Leviathan forges a covenant with Noctis and disappears. Titan's earthen wall grumbles and the tidal wave crashes toward the town, Lunafreya shielding Noctis on the now-ruined altar.
As depicted in Episode Ignis, Noctis's friends and Lunafreya's brother follow the events from afar. Imperial forces storm the town and Titan begins to battle imperial assault craft attacking him from the sky. Ignis Scientia and Ravus Nox Fleuret temporarily join forces to reach the altar where Ravus rushes to his sister's side. Ignis is intercepted by Lunafreya's Messenger dog Pryna, who delivers him a psychic vision of the future before perishing. Now knowing of Noctis's true fate should he continue on his quest to become the True King, Ignis finds Ravus by the dying Lunafreya, whose spirit departs despite his pleas for her to stay. Ravus blames Noctis for Lunafreya's death and attacks Ignis when the latter protects the still-unconscious prince. Ignis quells Ravus's aggression, but is soon met by Ardyn who at first wears Ignis's friend Gladiolus Amicitia's face as a disguise. When Ravus sees through the illusion Ardyn incapacitates him and Ignis is taken down by imperial soldiers.
Ardyn ponders over killing Noctis and ending any chance the world has for salvation. When Ravus interferes Ardyn blasts him into the altar with his magic. Ardyn offers Ignis a chance to join him and Ignis can either feign compliance, in which case Ardyn whisks him away to Zegnautus Keep, or fight back. Ignis grabs the Ring of the Lucii from the unconscious Noctis and puts it on. To Ardyn's surprise Ignis gains power from the Lucii at the cost of his vision, and the two duel until Ignis emerges victorious. Ravus acknowledges Ignis's feat and walks away, tentatively accepting Noctis is the world's only hope. Ignis and Noctis are saved by Gladiolus and Prompto, who take them away to recuperate.
The part of town destroyed, it is unknown what becomes of the altar after Leviathan's Revelation. Altissia is soon abandoned at the onset of the long night. Lunafreya is reported to having washed away in the tidal wave.
The location only appears in cut scenes in the main game.
In Episode Ignis, Ignis tries to reach the altar by boat, but is driven away by Caligo Ulldor on his magitek armor. After fighting Ulldor and teaming up with Ravus, the duo heads to the altar again, where Ignis fights Ravus and Ardyn as the final bosses of his episode. On the first playthrough, Ignis must refuse Ardyn's offer to go with him, but the player can play this alternative non-canon scenario after defeating the bosses.
There are some healing items the player can pick up during the boss battles.