Lost Cave (Japanese: かえらずのあなCave of No Return) is an island cave in the Sevii Islands, to the north of Five Island. Within the cave, the player can find and defeat Selphy, causing her to return to her house in Resort Gorgeous.
The cave lives up to its name of "Lost Cave", being similar to the Lost Woods featured in The Legend of Zelda series in that an incorrect turn brings the player back to the beginning. The rocks in each room hint at which direction the player needs to go, however, with the number of rocks indicating the clock position of the correct pathway to Selphy (3 = east, 6 = south, 9 = west and 12 = north). Deviations from this pathway will in most cases lead the player back to the room with the ladder and Lawson, however going the opposite direction from the prescribed path will, during certain points, lead to an item.
To retrieve these items, which are all in a room by themselves, the player must start from the room with Ruin Maniac Lawson:
The leftmost map with a BLUE inner border is the initial ladder room. RED-bordered sides return the player to the ladder room. WHITE-bordered sides lead to the adjacent room. GREEN-bordered sides lead to the next map to the right with a BLUE inner border.