The most dangerous place in the multiverse
Nobody knows how the Wormhole came to be, how it works, or why it exists. It has simply always been there, allowing travelers to cure their home sickness, gather new powers, or simply go on an adventure. Sometimes when a traveler enters, they bring a whole planet back with them. Othertimes they gain technology the rest of the multiverse cannot match. Other people simply never return, their fates unknown.
Out of Character wise, this is the location used to visit any area not provided by the board itself. The only requirement is a ship with Deep Space capabilities.
While rarely used due to its dangerous nature, a few important bits of technology have come from it. It was in the Wormhole that the armour used by GUN during the GUN Arc was located after many lives were sacrificed among other things.
Millenia ended up confronting her past through a trip in the Wormhole, and Serina had a run in with the UNSC by traveling in the Wormhole as well. Florina returned to her homeland through the Wormhole, at some point bringing the body of Hector with her.
Any region not in the multiverse can be reached.
If they have a location not in the multiverse, you can find them in here.
Anybody not currently or formerly in the multiverse.
Everything you could imagine. And then the rest you can't imagine.