Thoda Geyser (ソダ間欠泉 Soda Kanketsusen?) is a tourist-friendly, hot spring island in Tales of Symphonia. It is accessible through Thoda Dock and houses the Seal of Water, where the Summon Spirit Undine is fought during the story.
The first time the group arrives, they are looking for the "Spiritua Statue" a priest lost on his visit to the geyser. As they get from the docks, Colette Brunel notices something familiar from the distance but does not tell the group. At the geysers, Genis Sage uses Icicle to freeze the boiling water so that Lloyd Irving can climb on the frozen patches to reach the statue on the other side of the geyser. If Lloyd succeeds, he will obtain the statue on his own. However, if he fails, the party member with best attraction to Lloyd will come and save him, and Kratos Aurion will obtain instead. After obtaining the statue, it is possible to open the door that leads inside the geyser, which further leads to the Seal of Water.
Inside the geyser, the assassin from before appears again but is stopped by Noishe. After passing the Sorcerer's Ring's new challenge of water, the group is forced to fight the guardian of the seal. After doing so, Remiel appears again and gives Colette new angelic powers. When he has told them where to go next, he disappears, and the group decides to leave. However, outside, Colette collapses, and depending which route the player has chosen, Raine Sage will call this phenomenon Angel Toxicosis. If the more difficult route was chosen, Lloyd will ask Colette to look at her hand and tells her that she is bleeding from an earlier fall. However, Colette withdraws her hand and denies that it hurts. This makes Lloyd more suspicious, so he asks if he can talk to her alone. Colette waits while Lloyd returns with two cups of coffee. He gives Colette one, and after she agrees with him that the coffee is hot, he reveals that it is actually iced coffee.
Although shocked, Colette agrees with him but loses the coffee when Lloyd says that he lied—it is hot coffee. Colette finally confesses that she has stopped needing to eat and sleep, as well as that she cannot taste or feel anymore. Lloyd becomes angry and asks her why she has not told anyone, but Colette states she does not want anyone to worry—that it is her fate to become an angel. Although Lloyd is frustrated with her, she tells him not to tell it to anyone, for she wants the journey to be fun. Because of this, Lloyd hugs her and apologizes for not noticing before. Colette apologizes to him as well, saying she is happy and wishes she could cry, but that she cannot anymore.