The Old Mixer wrote:
King Daniel Into Darkness wrote:
The Enterprise in TOS and TAS visited the rim of the galaxy twice ("Where No Man..." and "By Any Other Name"), and the centre of the galaxy ("Magicks of Megas Tu") like it was nothing. By Voyager's standards, they would have been lifelong trips.
For the trips out of the galaxy, that's assuming that they went "horizontal" along the galactic plane. If they went "vertical" (at a right angle to the galactic plane), the galaxy is only a few parsecs thick in Earth's vicinity, IIRC. Which explains how and why the Valiant had left the galaxy so soon after the discovery of warp drive. Even at the low warp speeds of the time, it was a relatively simple thing to do.
And the engines were souped up by the Kelvans in "By Any Other Name", so that a transgalactic journey was feasible.
It's definitely the horizontal rim thet visited, according to "By Any Other Name":
ROJAN: There is an energy barrier at the rim of your galaxy.
KIRK: Yes, I know. We've been there.