Subspace turbulence is a subspace anomaly which causes severe disruption in subspace.
In 2153, during a ruse to gain information from the Xindi-Primate Degra, Captain Jonathan Archer had the pretend shuttle they were in experience subspace turbulence in order to make the deception feel as real as possible. (ENT: "Stratagem")
In 2372, while hiding from Vidiian patrols in a plasma drift, the USS Voyager encountered severe subspace turbulence resulting in power failures across the ship. The situation was later discovered to be the result of a subspace divergence field which had created two Voyagers. Eventually, a solution was found when one of the ships initiated its self-destruct, closing the rift for good. (VOY: "Deadlock")
A fleet of 15 Borg vessels created subspace turbulence in 2373. The turbulence disabled the warp field of the USS Voyager, which was in the way of the Borg's flight path. (VOY: "Scorpion")