The Lanes Between are vague pathways between Worlds, similar to Gummi Routes. However, these routes exist even when the worlds are guarded by their shields, are not comprised of the broken shields, and those who traverse them can enter the worlds without breaking the shield.
Lanes Between are opened similarly to Corridors of Darkness: through a portal. However, only a single portal is necessary for these, entering directly into the Lanes Between. They appear to be of both Light and Darkness - having both the dark appearance and black smoke of the Corridors, and thunderbolts and waves of light emanating from them.
Lanes Between do not need to be traveled via Gummi Ship - one can use a good many different vessels in order to traverse them.
They were heavily used during the time of the first Order of Keyblade Masters, when Gummi Routes did not yet exist. Keyblade Masters would utilize the "Keyblade Glider" ability and use their Keyblade as a vehicle to travel the Realm of Light and protect it from imbalance.
Several Out Worlds rely on the Lanes Between for their culture. The Space Ports use space cruisers to traverse the Lanes for trade and travel. Multiple worlds function under a single government and coexist with the help of the Lanes.
The Lanes Between are the only way to reach worlds whose Gummi shields have not been broken, and many worlds in the Out-Worlds regions, where worlds are simply too far gone to be reached even by the gummi routes they created.