Here’s where to find them:
Parapa Desert Overworld:
Location: In the Parapa Desert region (the path leading towards the first palace), head south. You will cross an overworld tile that triggers a side-scrolling bridge screen. Immediately after crossing this bridge tile, step onto the single grass tile found there.
Requirement: Defeat the red Goriya waiting inside this hidden area to claim the Heart Container.
Death Mountain (Requires Hammer):
Location: After obtaining the Hammer from the cave deep within Death Mountain, you’ll exit back onto the Death Mountain overworld map (near Spectacle Rock). Very close to this exit, you will see a large boulder blocking a small cave entrance.
Requirement: Use the Hammer ability to smash the boulder, granting access to the cave. The Heart Container is inside.
Southeastern Tip of Eastern Hyrule:
Location: Travel to the large island continent in Eastern Hyrule where the Three-Eye Rock Palace (Palace 6) is situated. Make your way to the absolute southeastern-most land tile of this large island mass.
Requirement: Simply step onto this specific corner tile on the overworld map. This triggers an item-found screen awarding the Heart Container.
Shallows Near Maze Island (Requires Boots):
Location: Find Maze Island (where Palace 5 is located) in the vast sea of Eastern Hyrule. South/Southeast of this island, you will see light-blue shallow water tiles.
Requirement: You must have the Boots to walk on these shallow water tiles. Carefully walk onto the specific shallow tile located directly south of the southernmost tip of Maze Island. Stepping on this exact spot reveals the final Heart Container.