Corridors of Darkness
Corridors of Darkness are unpredictable pathways that interlink the worlds of the Kingdom Hearts universe. The Heartless use these extensively to reach other worlds, as do members of Organization XIII, its subordinate Nobodies, and many other characters. These pathways are formed out of Darkness, so it is unsafe for a normal person to travel them, because the constant use of these corridors would corrupt one's heart. However, the Heartless and the Nobodies don't have worry about this, since the Heartless already have corrupted hearts, and the Nobodies do not have hearts to corrupt. However, one upside to this is that it provides a faster means of travel than the Gummi Ships.
Other characters who have used these corridors include Riku, Naminé, DiZ and even Pluto. Of these, only Riku, Naminé and DiZ have been responsible for summoning the portals, and only those lacking hearts to corrupt (Nobodies), and those who are darkness (Heartless) aren't affected, with two noted exceptions; According to Nomura in the Director's Secret Report XIII, Riku and Mickey aren't affected by darkness at all, due to some "secret similarities".
In Kingdom Hearts Re:Chain of Memories, DiZ says the cloaks protect from the darkness.
