The Portal

The Portal is an enormous energy doorway that allows practical, rapid travel between two distant locations, which appeared in the film Treasure Planet. It is possible the portal was also built by the ancient alien race that created Treasure Planet.

The Map that led to Treasure Planet also worked as the portal's control panel once plugged into a certain keyhole and would project an orbital list of locations. One touch on one of the projected destinations and the portal would instantly open a doorway to that destination, large enough for a ship to pass through.

Role in the Film
Captain Nathaniel Flint was known to use this portal to roam the universe, stealing treasure and would stash it at the centre of Treasure Planet. After Flint passed away, the Map was somehow recovered by Billy Bones and upon arriving at Treasure Planet, Jim activated the portal after figuring out the keyhole in the ground. Using the portal they were able to enter the centre of the planet where they found it piled with miles of treasure.

Trivia

 * The portal in may ways has some similarities to the Stargate as both are portal devices that hat allow rapid travel between two distant locations.