Ocean of Time

The Ocean of Time, as the Twelfth Doctor called it, was how exotic dimensional mathematics described the general state time took when time travel allowed the future to influence the past. By this perspective, all temporal existence was "one big oceanic moment" operating on principles of fluidity and flow on top of the more commonly-known principles of fixed points in time and the Flux of Potentialities.

The Doctor's time stream, constantly fluid by nature of its crossing itself in over a billion instances and its extreme future seeding its extreme past, was a prime example of the oceanic nature of time. The Vortex Butterfly saw that the shape of the time stream within the wider ocean of time was an eternal recursive spiral which branched off into New Selves. (COMIC: Vortex Butterflies)

Ancient Gallifrey at the foundation of the Time Lords had a similar fluidity due its relation with its own future. Alice Obiefune noticed that the version of Gallifrey's history she lived through had a slippery quality in her mind, as if details were always subtly changing after they occurred. She observed Rassilon was like the Doctor in containing multitudes, with details such as his appearance being hard to remember. (COMIC: The Lost Dimension)

Another example of the Ocean of Time was how Cindy Wu's travels in time allowed for the creation of her ancestors from her own DNA.

Rogue Vortex Artefacts had the ability to make metaphorical tsunamis which could make the Ocean of Time part and then crash back together in chaos. (COMIC: Vortex Butterflies)

The Time Sentinel went against the oceanic state of time embodied by the Doctor's time stream, considering them threats to the Web of Time. (COMIC: The Good Companion) They frequently cauterised timelines of Gallifreyan history to maintain a clean history, filling the Axis. (COMIC: Old Girl)