You need a starfish. There is one on Poseidon's statue in the museum on main street.
Get the pomegranates from the tree in the garden of the Sphinx, and put them on the altar.
first you get the starfish at the museum of poseidons face then go to poseidon castle and put the starfish there and go inside and you are at the beach
you put the starfish on Poseidon's offering altar.
To put the hydro scale on the altar in Mythology Island on Poptropica, you first need to obtain the hydro scale from Poseidon. To do this, solve the underwater labyrinth puzzle and find Poseidon's throne room. Once you have the hydro scale, return to the altar in the Grove of Temples and place it on the pedestal to activate the power of the gods.
Pomegranates. You get the three pomegranates from the tree above the creature in the Garden of the Sphinx.
Enter the temple to the right of the Muses, and put pomegranates on the altar. There is a tree just above the creature in the Garden of the Sphinx.
To open the door, when at the minator, jump up and find a pomegranite tree. Jump so that you hit the pomegranites and you offer them to Cerberus
you need to put it on the altar in hades lair to gain access to it
Put the starfish on the offering stand.
Pomegranates. You get the three pomegranates from the tree above the creature in the Garden of the Sphinx.
You have to get the starfish and put it on the offering alter.
In Mythology Island you get Hades Crown. When you complete Mythology, you get to use Hades Crown as a "Put On". Now you can put it on whenever you want!