You cannot open it until you have the aid of Hercules, and he will not do so right away.
Once you have all 5 sacred objects, you have to bring them to Athena at the Tree of Immortality, where their message can be revealed. Then they will be stolen by Zeus. Now Hercules will agree to help you, and he can move the boulders blocking you from Hades and from Poseidon.
get the five sacred items, give them to Zeus, go to Hercules, and use the mirror to get there.
His throne room is in the Temple to Poseidon, at the bottom of the lake. But you can only reach it when you have Hercules to move the boulder blocking the entrance. If you accidentally enter the Throne Room by slipping past the rock, you may not be able to get out again unless you have the Transporter Mirror.
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.
HERCULES!!
Once you have returned the 5 sacred items to the Tree of Immortality, Zeus will take them away from you. Now Hercules will help you move the rocks from the throne rooms of Poseidon and Hades.
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.
You cannot open it until you have the aid of Hercules, and he will not do so right away. Once you have all 5 sacred objects, you have to bring them to Athena at the Tree of Immortality, where their message can be revealed. Then they will be stolen by Zeus. Now Hercules will agree to help you, and he can move the boulders blocking you from Hades and from Poseidon.
Only Hercules can move the rock. Before he will help you, you have to collect the 5 sacred items and return them to Athena at the Tree of Immortality.
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.
you can't move the goat. there is no way.
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.
you get Hercules to move it