Stream Sanctuary is the underground water temple from Monster World IV. Throughout this dungeon, Asha must utilize Pepe's ability to blow out candles, rise from deep waters, and move platforms on the water using its breath.
The key item procured here is a bucket that can be filled at various points. The water can then be used to put out large fires that block the player's path. The boss at the end of this dungeon is the Water Wizard.