Jump gate

A vortex forms in a jump gate.

A jump gate is device that creates a vortex into hyperspace to provide ships that lack their own jump engines with a means of interstellar travel.

John Sheridan once used a jump gate as an improvised weapon to destroy a Shadow ship. With the vortex in the jump gate still open, he used the hyperdrive on his own ship to open another vortex inside the first one. This event created a massive explosion as all of the energy being used to maintain both vortexes was released at once.