Stuck in Mermaid's Cave with a door that ignores your keys, a missing Small Key that is actually on the other timeline, no Mermaid Suit yet, a confusing Boss Key loop, or Octogon swimming where you cannot follow? This is Dungeon 6's dual-era trap: Present and Past are two different floors. Use the short answer, then track every phase.
Prerequisites Stuck diagnosis Route cards Step checklist FAQ
Mark gear and story progress you already have. Saved in this browser only.
Match what you see in-game to a cause and a fix.