A rare and highly unusual subspace compression phenomena was discovered in 2374. The anomaly caused an object which passed through it to be greatly reduced in physical size; the Danube class runabout Rubicon was shrunk to a size of approximately a dozen centimetres while investigating the anomaly, although it was eventually able to return to its normal size. It was hoped that study of the anomaly would enable a better understanding of the mechanisms behind transwarp conduits to be gained.

 
A phenomena which indicates the presence of a functioning warp drive system. The Cytherian probe encountered by the Enterprise-D in 2367 did not generate any subspace field distortions even though it was capable of travelling at faster than light speeds. The nature of the probes drive system remains a mystery to federation science.

The region around the Hekaras corridor is rife with subspace instabilities and it was here that the damaging effect of warp drives was proven when Dr. Serova created a warp core breach in her ship, resulting in a subspace rift. As a result the local inhabitants feared that they would have to abandon warp drive altogether, but in fact a modification to warp engine design has allowed vessels to operate without damaging space in this manner.

 
Our universe coexists with a multitude of others which occupy the same physical space but are separated by the phase difference between them. Occasionally our universe overlaps one of these others, creating a region of interphase. Such interphase pockets are highly dangerous; vessels entering them are likely to find themselves marooned in another universe with little chance of returning. Being in close proximity to an interphase pocket has drastic effects on the brain function of Humanoid life forms, while being trapped inside one is generally fatal.

In 2268 the USS Defiant wandered into an interphase pocket. The effect of the pocket induced intensely violent behaviour patterns in the crew, causing them all to kill each other. When the USS Enterprise investigated the phenomenon Captain James Kirk led a team onto the Defiant. The Defiant began to shift into another universe and Kirk became trapped inside the interphase pocket as his team was beamed back to the Enterprise. He survived for several hours in the pocket, having been protected during the transition by the cushioning effect of the transporter beam, and was eventually recovered. Unfortunately the Defiant herself could not be salvaged.

Interphase pockets are highly sensitive to disturbances in space and any use of energy in their vicinity can cause them to shift position and alter the timing of the periods of interphase significantly.

 
An opening in the fabric of normal space through which subspace protrudes. High level exposure of space containing subspace instabilities to warp fields can result in a subspace rift, causing vessels to become trapped. The rifts are extremely sensitive to any use of subspace technology, most especially to warp drive - any use of a warp drive system within a rift causes it to expand greatly.

In 2370 the USS Enterprise was present at the formation of a subspace rift in the Hekaras corridor, and was subsequently trapped within it when the USS Flemming activated its warp drive. The Enterprise managed to escape the rift, but was unable to do anything to repair it. For a time all Starfleet vessels were limited to speeds of no more than Warp 5 in order to prevent the cumulative damage to the fabric of space from creating more rifts, but new models of warp engine are able to operate safely at any speed and the warp 5 limit has been abandoned.

 
A large anomaly which acts in a manner similar to a whirlpool, sucking matter into it over a large scale. In 2169 a Vulcan vessel discovered a subspace rupture in the Hanoli system. The Vulcans detonated a pulse wave torpedo in the rupture, setting off a chain reaction which destroyed the entire system.

In 2369 the crew of Deep Space Nine believed that a subspace rupture had formed near the station, but the anomaly proved to be a manifestation of their imaginations created by an alien species investigating Humanoid mental processes.

 
A shock wave produced by certain types of explosion, most notably those involving dilithium ore. Subspace shock waves tend to propagate across an almost flat plane rather than in the three dimensional manner of a normal explosion. The shock wave propagates through normal space and can interact with objects within our universe, but its subspace nature allows it to travel at high multiples of the speed of light. The near destruction of the Klingon moon Praxis in 2293 produced a large subspace shock wave with a double wave front which extended out of Klingon territory altogether and hit the USS Excelsior, which was patrolling in the area at the time.

 
A subspace tear can be created by an isolytic subspace weapon. It allows a portion of subspace to intrude upon normal space, presenting a threat to Starships in the vicinity. The tear can be attracted to a Starships warp core, which drags it across space like a zipper. Detonating such a warp core within the tear can cause it to close up again, although this is not guaranteed. Such a tactic was successfully employed by the Starship Enterprise-E when a Son'a vessel used a subspace weapon against it during the Ba'ku crisis.

 
A phenomenon associated with the dimensional shift transport technology employed by the Ansata terrorists on Rutia IV. Virtually undetectable by conventional sensor systems, the effect can be scanned with accuracy by an adaptive subspace echogram. In 2366 the USS Enterprise used such a scan to locate the Ansata headquarters and score a major victory over the Ansata.

 
A natural subspace phenomenon which links two points in space time and causes matter and energy located at each point to switch places with its counterpart. The two points can be separated by virtually any distance, or for that matter could even exist within other dimensions. Subspace vacuoles are attracted to the warp cores of a Federation Starship.

In 2371 USS Voyager encountered a planet whose rings were riddled with subspace vacuoles which linked it to the Vhnori homeworld. The Vhnori had been sending their corpses through the vacuoles for a long time, believing that the phenomena were conveying their dead to the afterlife. When Ensign Kim was accidentally transported through a vacuole to their world he revealed the true destination of the vacuoles and revealed that he had seen the bodies of the Vhnori dead before being transported to their world, confirming that this aspect of their religion was in fact false. This prompting something of a religious crisis on the planet. When he - eventually - realized that such revelations were a prime directive violation Kim effected an escape through another vacuole back to Voyager.

Captain Janeway subsequently noted that the Vhnori beliefs may in fact have had some slight basis in reality, since the planet the dead were being transported to was surrounded by a very complex energy field which might contain the neural patterns of the dead Vhnori. Whilst this may be true, an afterlife as disembodied energy remains fundamentally at odds with Vhnori beliefs as revealed to Ensign Kim.