Sand Portal

"Have you ever heard of the Sand Portal? It's a sand castle that appears, then crumbles away quickly. I guess it must not have a very good foundation..."

- Pianta

The Sand Portal is an extremely thin sand castle that is found only in the first mission of Gelato Beach ("Dune Bud Sand Castle Secret") in Super Mario Sunshine. It is temporarily created via a Dune Bud located relatively close to the location on the beach in which it appears, and will immediately begin to disintegrate the second that it pops out of the sand, eventually reforming back into the surrounding sand. Therefore, Mario must immediately make his way to it as soon as the player has sprayed the Dune Bud with water from F.L.U.D.D., or else he will have to travel back to the Dune Bud and spray it a second time to make the sand castle appear once again.

There is only one way to enter the Sand Portal, and that is via a small, arched doorway located on its front. As soon as the sand castle pops out of the sand, a rotating red arrow will appear, guiding the player to the arched doorway as the sand castle gradually crumbles away. Though the doorway appears to lead straight through the Sand Portal to the other side of the castle, when Mario enters it, he will be instantly transported to a secret level (though he can enter the Sand Portal from the other side of the doorway as well), which he will have to traverse in order to recover the Shine Sprite for the level. The first time Mario enters the level, F.L.U.D.D. will be taken from him by Shadow Mario, but if Mario enters the Sand Portal after this, he will be allowed to use F.L.U.D.D. to make his way through the secret level.

Trivia

 * While the Sand Portal is created via a Dune Bud, it is different from the other sandy structures that are created by Dune Buds because it gradually sinks back down into the sand once raised, as opposed to sinking back down immediately, and also because it appears far away from the Dune Bud that creates it, as opposed to appearing directly under it.