Wonder Boy in Monster World/Hearts

Heart containers are what increase your maximum life, you collect them from chests, they are NOT the hearts enemies drop so don't worry about missing them. Also Wonder Boy in Monster World is completely open world, you can back track anywhere you want so if you miss any of them you can go back and pick them up later.

1. In the first dungeon before you open the 3rd ocarina door there is a chest above you just before the spikes. VERY hard to miss.
2. You need the dwarf companion with you to be able to reach this one. In the second dungeon you need to avoid the rolling ball and duck under it to the right at the bottom on the hill. Head all the way through this tunnel and you will come to a ladder, head right and climb another ladder. Head left and into the next screen. Hit the switch and go right, back into the area you just left. The steps you just jumped over now lead down to breakable silver blocks. Break the blocks and walk in. (Don't go too far there is a false floor at the very end) Your dwarf buddy will smash a wall about halfway in. Head through the hole and claim your heart.
3. After the second dungeon and having obtained the trident, head all the way back to the very beginning of the game. When you get to the part with the jellyfish that you bounced across the first time, jump into the water with the trident equipped. Swim to the left and you will see a small gap in the wooden wall, in there is the chest.
4. In the cave where you kill the knight and save the princess, the second body of water from the right has a secret door at the bottom. You need the trident to get to it. Push up at the very bottom, to open the secret door. Follow the path and find the chest at the end.
5. In Poseidon's Cave, when you come to the part where you need to disable the 2 fans. One switch is on the top floor, one is on the bottom. The heart is in between the 2.
6. In the third dungeon (the Ice one) when you get to the part where you would jump up to find the boss door, instead head all the way left and jump into the door on the tower.
7. Once you have obtained all the pygmy armour. Head into the door just to the right of the dragon village to turn small. Once small head back to the second dungeon in the forest. Once there head down the first ladder and go through the small opening to the left and into the small door. On the other side is the Chest.
8. While as a pygmy, (as described above) backtrack from the dragon village to the pyramid via the left path. Once there drop all the way down and through the small opening, push the switch and drop down, from here head left and through that small opening. Drop down and walk through the wall on the left (it looks solid but it's not really) (The doors here hide a lot of chests with treasure in them).
9. While in the volcano, you will do a lot of moving forward, pushing a switch and then backing up to find an opened passage. When you reach the switch where a fireball chain comes out to your left, kill it and jump down into the lava. You will fall straight through and find the chest with the heart and an exit door.
10. Once you have obtained the Legendary Sword and travelled up into the clouds, head left until you come to a cloud platforming section. Here you should be able to see the chest above you. To get to it you need to traverse the clouds right and then come back left on the row higher up.
11. The final heart is inside the Castle right after the section mentioned above. Once you come to the section where you can jump onto the mine cart go past it and head all the way to the bottom. Once on the very bottom track head all the way left and push up. You will enter a secret pygmy door. Once you are through that head right and drop down. Head right and back up the rope to the mine cart. Jump on the mine cart this time and travel down and jump onto the platform next to the rope. Climb up the rope and grab the small rope that will take you across the spikes. Once there Drop down the hole to the right. (Legendary Armour chest is right here) From here go through the small opening and find your chest.