Xindi ships emerge from a subspace vortex.
The subspace vortex (also called a spatial vortex, energy portal, or subspace corridor) is an extremely fast method of transportation utilized by the Xindi.
Though Gralik Durr claimed they had a range of only a few lightyears (ENT: "The Shipment"), vortices were actually capable of transporting a ship from the Delphic Expanse to Earth in ten hours, a voyage that would take a warp five vessel six weeks (ENT: "Countdown"). Unlike warp drive, 22nd century phasers can be fired in a vortex. (ENT: Countdown) The larger a vortex is, the more unstable. Degra said he would have great difficulty creating a vortex large enough to carry the Xindi superweapon and four other vessels; he warned one or two of the ships might be destroyed. (ENT: "Azati Prime")
Enterprise enters the subspace corridor
The Xindi maintained a permament one-way subspace corridor that extended 11.6 light-years from a nebula inhabited by Kovaalans to not far from the Xindi Council planet. In February 2154, Enterprise used this corridor to quickly travel to the Council planet. (ENT: "E²")
- In an alternate timeline, Enterprise traveled through the corridor with a damaged impulse manifold. The particle wake destablized the corridor, causing it to shift in time. The ship emerged in the year 2037. Fortunately, this was avoided when that Enterprise assisted the 2154 version of the ship in making alterations to the impulse manifold.