Once you have recovered the Five Sacred Items (pearl, hydra scale, minotaur ring, flower, and whisker), you cannot immediately enter the Throne Rooms, because it will take the strength of Hercules (and he won't help).
Instead, return to the Tree of Immortality where Athena will help you assemble a secret message on the items. When Zeus appears and steals them, Athena will send you back for Hercules, who will finally agree to help you reach the two Throne Rooms.
On Mythology Island, you will meet the god Zeus, and his daughter Athena at the Tree of Immortality. You will find Aphrodite on the beach in the realm of Poseidon. The gods Poseidon and Hades are in their throne rooms, which you cannot enter until you have recovered the 5 sacred items and returned them to the Tree of Immortality.
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.
** For the complete solution to the island see the related question below **After recovering the five sacred items, you cannot access the thrones of Hades and Poseidon right away (although you might slip past the rock blocking the way underwater).When you have recovered the Five Sacred Items, bring them back to the Tree of Immortality. You must assemble the message on the items, and Zeus will arrive to take them away. With the help of Hercules, get the Trident of Poseidon and the Crown of Hades, and go to Mount Olympus to battle Zeus.(see related question)
Once Zeus has taken the 5 sacred items, Hercules will agree to help you, and will move the rocks blocking the way to Hades and to Poseidon. (You will need the Touchscreen Mirror from Aphrodite in Poseidon's realm.)
how do you get the red rose on mythology island from poptropica?
Poseidon is found on Mythology Island, which is a Poptropica island.
From Poseidon's statue in the museum.
The only doors on Mythology Island are at the temples of Hades and Poseidon, and on the Minotaur's lair.
the pink starfish
In Poseidon's realm, you click on her.
It is in the museum, on the face of Poseidon's statue.
If you are talking about Mythology Island, there is no such thing there. Mythology Island only has three 'kingdoms': Hades, Poseidon, and Zeus.
Offer the starfish from the Poseidon statue in the Museum.
The offering for Poseidon is a starfish. There is one on the face of his statue in the Museum of Olympus.
zombie poptropica
all you need is Hercules's help
You need a starfish. There is one on Poseidon's statue in the museum on main street.