Time travel is the ability to move from one point in time to another outside the regular, irreversible flow of time. The act of moving through time has the potential to alter the timeline or create whole new realities, such as the Kelvin Timeline and is thus discouraged. As a result, time travel is rare even though there are several natural and artificial means at the disposal of major powers.
In the 25th century, the Alliance powers devised more predictable means of time travel during the Iconian War. This led to their greater involvement in the Temporal Cold War. The Alliance usually prohibits any alteration of the timeline, the notable exception being during the Iconian War. Other powers, such as the members of the Temporal Liberation Front wish to improve the timeline by selective interventions in the past.
By the 29th century the Federation and other Alliance members are major temporal powers and were key movers behind the eventual signing of the Temporal Accords.
“Painful Omens”: Features Na'kuhl from the future, a temporal anomaly and Daniels explaining things from the future.
“Return to Babel”: The player travels back in time to prevent assassins from the future.
“Tangled Webs”: The player is sent by Daniels, from the future, to the past to prevent Na'kuhl from the future destroying Tholian ships which would start a war with the Federation. Ends with the Defiant about to travel back in time into the mirror universe to then alter events there.
“The Battle of Caleb IV”: Includes Kor being manipulated from the future by the Envoy, and Daniels saving the player by bringing them into the 25th century to work as a temporal agent.
“Cold Storage”(Delta Recruits only): 18 months after meeting their future self, the player is sent back in time to complete the cycle of events by warning their past self of the approaching Iconian War and giving their past self a Tesseract Communications Receiver. The player then returns to the present.
“Midnight”: The player travels back 200,000 years to the day that the Iconians are forced from their homeworld, with the purpose of wiping out any survivors. Instead, the player saves 12 Iconians and returns to the present, returning the World Heart to them.
“The Core of the Matter”: The player travels back to the 23rd century, encountering Na'kuhl from the future.
“Vorgon Conclusions”: The player travels to the Lirss System in the future to meet Daniels from further in the future to protect Kal Dano who is about to travel earlier in the player's timeline to when they first met Kal Dano and hid the Tox Utat. When they catch up with Kal Dano it is much later in his timeline but in the 22nd century when Kal Dano is dead and being attacked by Suliban being given orders by the Envoy from the future. They then travel to the 24th century to find where the Tox Utat ended up after that and destroy several Breen ships of the era. There they find the Vorgons from the future and the Envoy from their own era before recovering the Tox Utat.
“Terminal Expanse”: The player travels back to the 23rd century, but to an alternate reality.
Tholians use the Tox Uthat, stolen from the time travelling scientist Kal Dano, on the star of the Na'kuhl System. Dano and the player subsequently retrieve the device from the Tholian flagship and travel back the 22nd Century where they hide it in a cave on Risa. After returning to 2410, Kal Dano vanishes into a time vortex during a renewed fight against the Tholians in the Na'kuhl System when his Timeship is damaged. He sends a temporal distress call before entering the vortex which prompts the U.S.S. Pastak to arrive from the 29th Century and investigate. After Captain Walker invites the player to the Pastak's bridge, they manage to retrieve Kal Dano's decayed corpse and Timeship, which had travelled back to the early 22nd Century where, a few decades later, the crew of the Enterprise (NX-01) inadvertently activated the Timeship's temporal distress beacon, causing it to automatically travel back to 2410.
“Time and Tide”: The player's faction has been contacted by the 29th century for the player to visit the 28th century to view the signing of the Temporal Accords. The accords are interrupted by an attack by Noye so the player then travels back to confront him. Noye then travels forward to escape the player, then back again (much later in his time frame, but a few minutes in the player's) to fight the player. He then escapes in a temporal vortex which the player also enters, but fails to catch him as he shifts in time again.
“The Temporal Front”: The post-war peace conference is interrupted by an assassination attempt by Krog from the 29th century. Walker from the 29th century brings the player forward to confront them and they find Vosk preparing to go back in time, including to the 20th century. The player prevents most of the Na'kuhl but Vosk escapes to the 20th century where he is eventually stopped by Captain Archer, who Daniels sent from the 22nd century.
“Survivor”: A temporal duplicate of Admiral T'nae (caused by the time travel in Temporal Ambassador) is causing temporal anomalies. These anomalies cause time to pass far quicker or slower inside them than the surrounding space.
“Temporal Ambassador”: The Enterprise-C, which was sent from 2366 (following the events of "Yesterday's Enterprise") to go back to the Battle of Narendra III in 2344, accidentally ends up in 2409, resulting in a vastly altered Alpha Quadrant in which Earth is destroyed and Starfleet is a memory. The 29th Century timeship U.S.S. Pastak makes an appearance to help set things right.
“Sunrise”: The Tholians lure Kal Dano to the present from the 31st Century by destabilizing the Lukari star, planning to steel the Tox Uthat. Kal Dano loses the Tox Uthat to the Tholians after repairing the damage to the star, telling the player that these events are tied into the Temporal Cold War.
“Echoes of Light”: Deep Space K-13 is discovered to have been transported through time from the 23rd to the 14th century and has been abandoned ever since.
Timeships are vessels that have travelled forward or backwards in time. This includes all starships with "Temporal" or "Timeship" in the formal name, as well as any other starship that can utilize Molecular Reconstruction or other temporal-related abilities or weapons.
The majority of these playable starships are from the past or future, relative to the 25th century.
“Graduation Day”, 
26th century Federation starships, Tier 6
Universe-class
Durgath-class
Valkis-class
Paradox-class
