Last week Trenitalia posted an update on the Civitavecchia service for 2022.
The timing doesn't work for most cruise passengers unless their cruise ends in Rome but here it is.
There is one morning CE train departing Civitavecchia at 9:07, arriving to Roma S. Pietro at 10:00 and Roma Ostiense at 10:10.
There is one afternoon run departing Roma Ostiense at 16:30 (4:30 PM), stopping at Roma S. Pietro at 16:43 (4:43 PM) and arriving to Civitavecchia at 17:20 (5:20 PM).
The fare is 10 euro each way, or 15 euro if you purchase both tickets together. Children up to 12 years of age ride free with an adult. This press release doesn't specify it but usually that means one child per adult. There is no fee for baggage.
You are guaranteed a seat on this train, they only sell as many tickets as they have seats, but seats are not assigned. Note that this means if the train is sold out, any children under 12 will not get a seat.
Trenitalia hasn't gotten around to updating the English language page on this topic but you can read the information here using google translate, if necessary: Ferrovie dello Stato (trenitalia.com)
