first, go to the muesuem and get the star fish. then just click USE and place it on the trophy looking stand next to the door
hercules
you get a pomagranet from the garden of the sphinx and place it on Hade's alter at his palace. The alter is by the door. The door will then open.
give him ten darchmas
you need a pomegranate from above the sphinx
To open the underground door on Mythology Island in Poptropica, you need to retrieve the trident from Poseidon. Once you have the trident, use it to unlock the door and access the underground area. Good luck!
Offer the starfish from the Poseidon statue in the Museum.
You click on the snake with the red eyes when he comes out of the picture. Then it will open the door!
you find the door next to the big lion thing and after you get the flute you play the colors on the door.
To open the door, you need to play Blue, blue, green, yellow, yellow, red, blue, green.
You have to go underwater which is left to Aphrodite and you have to find a clam. It opens and closes. Try to get the pearl (which is inside the clam) when the clam is open.
They DON'T open both. The pomegranates only open Hades' door to the underworld put them on his alter in Mythology Island. To open Poseidon's door to his his awesome beach, you need the starfish off of his statue in the museum.
Place it on the offering stand in Hades throne room.