When explorers entered the Swamp Palace, they were unable to cross the empty indoor canal because of its steep, shear sides. The key to getting to the other side was understanding the connection between the Light and Dark Worlds. Standing just outside of the palace, adventurers would warp to the Light World Watergate and pull the switch inside, allowing the water to flow. Then they would return to the Swamp Palace in the Dark World and swim across the water-filled canal. Go here for an enemy list and boss tips.