We will be in Trieste IT in late September and would like to visit a northern Croatian port or two. Rovinj looked interesting and beautiful. Can you get from Trieste to Rovinj that time of year by ferry?
The couple ferry lines up this way run with very limited schedules, and I had a hard time finding much on them even then. Like, they only operate in the highest of high season. Bus would be a better option, and probably faster too. Check out Brioni and Flixbus lines. I’ve good experiences with both (Flixbus has a better website/app imo, a little more modernized support.)
https://www.croatiaferries.com/slovenia-ferries.htm#google_vignette
Just google Croatian ferries,. Good luck.