Forest Temple - Piece of Heart Locations
There are two pieces of heart for you to find in the Forest Temple. They are in adjacent rooms but depending on which version of the game you're playing - the directions will be different. The version I took these screen shots with is the Gamecube version so if you're playing the Wii HD remake the directions will be reversed for you.
Additionally if you need to enlarge any of the pictures to see where I am at or what I am doing - just click on them!
Forest Temple - Second Heart Piece
This Heart Piece is the first one found in the Forest Temple and it's quite close to the dungeon entrance. In the room with the large wooden platforms you'll find a chest behind one of the carnivorous Deku enemies. In order to reach this chest you will want to smack a Bombling up top and toss it down into the plants mouth. Behind this plant you'll find a chest with the Heart Piece, as seen in my screenshot.
This is much easier said than done since you have to come to a complete stop in order for Link to sheath his sword. Maybe I'm retarded and there is a better way, but if you're like me and you were unable to get it through on your first clear of the Forest Temple come back once you get Bombs and the Clawshot and you'll be able to reclaim your prize.
Forest Temple - Third Heart Piece
The second piece of heart for you to get in the Forest Temple can be acquired after you get the Gale Boomerang. You'll want to return to the room with the worms under the tiles where you had to light the torches earlier. This time instead of lighting them you'll want to put them all out.
Lock onto them all at once or one by one to put the torches out and to reveal the hidden chest behind the wooden stairs we took earlier.