Subspace corridor

A subspace corridor is a shortcut through space, which can allow a starship to traverse great distances otherwise unachievable with traditional warp drive.

In the 22nd century there was a subspace corridor in the Delphic Expanse, extending 11.6 light years, from a nebula controlled by the Kovaalans, to not far from the Xindi Council planet. In February of 2154, the entered this corridor in an attempt to quickly travel to the Council planet. However, due to battle damage sustained in combat with the Kovaalans, Enterprise's impulse manifold produced a particle wake which caused the corridor to shift in time. Enterprise emerged in the year 2037, and the crew quickly realized that, due to the corridor's one-way nature, there was no way for them to return to their own time. Enterprise became a generational ship, and the crew's descendants were eventually able to change history by intercepting their counterparts in 2154, and assisting them in making modifications which corrected the damage to the impulse manifold. This allowed Enterprise to safely pass through the corridor without traveling back in time. 

In the Delta Quadrant, the Vaadwaur used a vast network of subspace corridors called "Underspace" to aggressively expand their territory, until they were defeated in the 15th century. In 2376, the starship USS Voyager was accidentally pulled into Underspace. They were subsequently forced out by the Turei, a species who had appropriated the corridors, who targeted Voyagers shields with a resonance pulse, altering Voyagers shield harmonics and returning them to normal space. 

In 2377, Reginald Barclay speculated that a group of Ferengi may have found either a wormhole or a subspace corridor to bring Voyager to the Alpha Quadrant, before realizing that they were planning to utilize a geodesic fold.