Transwarp conduit

A transwarp conduit, also known as a transwarp corridor, was an artificially-created energy conduit through a realm of subspace known as transwarp space. They were utilized by the Borg to cover great distances in a relatively short period of time. Accessed via tachyon pulses of alternating frequencies, the conduits contained a matter stream in which a vessel could reach velocities at least twenty times greater than the maximum warp speed of a starship, in a process Lieutenant Commander Geordi La Forge described as "like falling into a fast-moving river and being swept away by the current." 

Technical data
The generation of a transwarp conduit was characterized by triquantum waves, subspace disruptions with a field magnitude of at least 2.9 teracochranes, and a highly-symmetric power-utilization curve. The Borg maintained a network of thousands of transwarp conduits throughout the galaxy, connected by six transwarp hubs supported by interspatial manifolds, with exit points in all four quadrants. They were additionally able to generate new conduits through use of transwarp coils. This allowed the Borg to deploy vessels almost anywhere in the galaxy within minutes, giving them a decisive tactical advantage. Upon entering a conduit, a vessel was subject to extreme gravimetric shear. To compensate for this, the Borg projected a structural integrity field ahead of the ship. Additionally, there were extreme temporal stresses placed upon the vessel, necessitating a chroniton field be projected throughout the ship in order to keep the different sections of the ship in temporal sync. 

Encounters
In the 2350s, after three months of shadowing a Borg cube aboard the USS Raven, Magnus and Erin Hansen followed in the cube's wake after it entered a transwarp conduit, traveling all the way to the Delta Quadrant, the Borg's native territory. 

The crew of the USS Enterprise (NCC-1701-D) observed a transwarp conduit in use in 2369, while engaging in combat with a rogue Borg vessel. Pursuing the vessel, the Enterprise became caught in the conduit's energy matrix and was briefly pulled inside. Later, upon analyzing the subspace distortion of the conduit, Commander La Forge was able to reproduce the tachyon pulses the Borg used to open the conduit, allowing the Enterprise to pursue the Borg to the planet which they were using as a base, sixty-five light years away. 

In 2374, the USS Defiant (2370) was sent to investigate a subspace compression anomaly. Starfleet believed that analysis of the phenomenon would provide them the knowledge to create transwarp corridors that could help them win the Dominion War. 

During the same year, Seven of Nine attempted to utilize the USS Voyager's main deflector to generate a transwarp conduit in an effort to facilitate their return to the Alpha Quadrant. Erratic fluctuations of the ship's warp power caused the tachyon levels to rise to a resonant frequency. Tachyons flooded the warp core, threatening a breach. Unable to stabilize, Lieutenant Torres was forced to eject the core. 

A year later, Kathryn Janeway, Voyager's captain, mounted a mission to steal a transwarp coil from a Borg sphere, in an attempt to return to the Alpha Quadrant. The mission was successful, but the Voyager crew was forced to install the coil in the Delta Flyer in order to travel to Unimatrix 01 to rescue Seven of Nine. Upon completion of the mission, they returned through the conduit to rendezvous with Voyager, pursued by a Borg ship. As soon as the Flyer arrived at Voyager's coordinates, Commander Chakotay ordered a full spread of photon torpedoes fired at the threshold perimeter of the conduit, destabilizing the matter stream and imploding the conduit for at least a light year. This resulted in the destruction of the Borg vessel upon emerging from transwarp space. Voyager was subsequently able to travel another twenty thousand light years towards the Alpha Quadrant before the transwarp coil gave out, eliminating approximately fifteen years from their journey. 

In 2378, Voyager discovered a transwarp hub in a nebula, allowing them access to a transwarp aperture less than a light year from Earth. With help from her counterpart from twenty-six years in the future, Captain Janeway was able to outfit Voyager with ablative generators, enabling the ship to withstand attacks from Borg ships guarding the hub. Entering the conduit, Voyager destroyed the interspatial manifolds as it went, causing the hub to collapse. Despite their destruction of the manifolds, Voyager still found themselves pursued by a Borg sphere, which exited near Earth and engaged a fleet of Starfleet vessels. Voyager destroyed the sphere from within using a transphasic torpedo, an advanced weapons technology acquired from Janeway's counterpart.