Before Hercules will help you, you need to get the five sacred items and take them back to the Tree of Immortality.
You will also need the Touchscreen Mirror from Aphrodite's test on the beach in Poseidon's realm. The gods in her test are Ares, Hermes, Aphrodite, Artemis, and Hestia.
HERCULES!!
In order to move the rock on Mythology Island in Poptropica, you need to find Hercules, who is located in the Hercules' Hero Hut area. Hercules will lend you his strength and help you move the rock.
you get Hercules to move it
To move the boulder on Mythology Island, you need to obtain the Golden Apple from Hades in the Underworld. Offer the Golden Apple to Atlas, who will then help you move the boulder so you can access the entrance to the Underworld.
If its on mythology island, get Hercules to move it for you. press the skull on the mirror and Herc will move it for you.
To move the rock in the underworld on Mythology Island in Poptropica, you need to acquire the Titan minotaur's ring. Once you have the ring, go to the cave entrance in the Grove of Temples and use the ring to summon the Titan minotaur, who will move the rock for you.
The entrance to the Underworld (realm of Hades) is in the Temple of Hades. Put pomegranates (from the garden of the Sphinx) on the altar to open the door. You cannot move the rock from the throne room. Only Hercules can do that, and not until you have collected the 5 sacred items and returned them to Athena at the Tree of Immortality.
5 rounds of jumping ducking and moving
get the five sacred items, give them to Zeus, go to Hercules, and use the mirror to get there.
To move the rock in Mythology Island on Poptropica, you need to complete the tasks for each of the gods. After you have completed the tasks for Zeus, Poseidon, and Hades, you will receive a special item that will allow you to move the giant rock blocking your way.
After you collect all five sacred items, return to the Tree of Immortality. Zeus will take them. Then you can go to Hercules and talk to him. Use the Touchscreen Mirror to teleport to Hades throne room and Hercules will move the boulder.
with Hercules, use the mirror Aphrodite gave you to travel to the underworld. there Hercules will move the bolder for you and you must go in and speak with Hades. there he will give you the helm.