Cinque Terre

You can take the train like I did.
Search Trenitalia.com https://www.trenitalia.com/en.html and pick the quickest route or the one with 1 connection.

However the schedule currently only goes up to June 10 (or normally about 90 days in advance).
Also when searching you always have to use the Italian spelling for the town and/or the train station.
For example Florence would be Firenze S. M. Novella.
Also you need to pick a specific town of the 5 (Cinque Terre) as your destination when you search:
For example either Monterosso, Manarola, Corniglia, Riomaggiore, or Vernazza.

As things are going with the pandemics and the current vaccination rate I’m not sure Italy will have removed the current travel restrictions by this summer.

During normal times the most efficient way to travel to the Cinque Terre from Florence is by train. There are numerous departure times but all of them will require at least one train change at Pisa Central and/or La Spezia Centrale.

www.Trenitalia.com

Right now, you can take a train to Pisa from Florence and transfer to Monterosso which is the town that’s furthest north of the Cinque Terre villages. The total trip takes 2h 30m.
Another option is to store your backs in lockers at the Pisa train station and see the leaning tower before continuing your journey to the Cinque Terre.

Ditto to all of the above: train is the way. I just checked on an option that used to be the fastest way (Firenze Campo di Martre station to La Spezia Centrale at 7:54 AM; 1 hr, 43 minutes, no changes) but I'm not seeing it. Could be because of reduced COVID schedules + it's low season so keep checking. From La Spezia, you'd take another train into the region: choose Riomaggiore, Manaola, Corniglia, Vernazza or Monterosso as your final destination.

Just in case you're thinking of doing so, I don't personally recommend the CT as a day trip from Florence 'cuz the BEST hours are when the hordes of daytrippers are not around. This is especially true during high season! For the optimal experience, I recommend at least one night if not two.

Agree that day trip from Florence to CT might be a bit much. We stayed in Lucca for a few nights and took a day trip from there. And that way you can enjoy Lucca also, a wonderful city!

Ozzy,

As others have mentioned, with the current pandemic situation in Italy, I'm not sure travel there will be possible by summer 2021. However if you do manage to get there, that's an easy trip by train.

It wasn't clear from your post if you plan on travelling to the Cinque Terre on a day trip, or whether you plan to stay there for a few days? Which rail connection to use will depend to some extent on the answer to that question.

If you are going after June 13, do not keep on checking: check only once on June 12 when the complete schedules up to December 13 will be uploaded on trenitalia.com/en.htm

Use " Firenze (Tutte le Stazioni) " as departure point and an hour of departure before 7 AM.

The main change internally in Italy at this point that the pandemic has had is that it’s illegal for even residents/citizens to leave their own regions, so travel from Florence to Cinque Terre would be a no-no. (In fact, under current restrictions, only people in orange zones can visit one other household within their own region and then only on Easter weekend. Until then they can only visit one other household in their same commune.

• People residing in Red Zones can’t visit others at all, even in their same commune. They will have the ability to go see another household during one day of the Easter weekend within their own region.

That may have changed by “summer,” but I wouldn’t count on it 100%.

Then there is the other pesky question depending on your country of origin and whether you are allowed to enter Italy for tourist purposes (if that is indeed why you plan on going). I’ll presume you have already looked into that part of the equation. Of course again, while U.S. tourists are not currently allowed to enter Italy, it’s not clear whether that will be the case by “summer,” so you have to keep a constant eye on it.

Right now, you can take a train to Pisa from Florence and transfer to Monterosso which is the town that’s furthest north of the Cinque Terre villages. The total trip takes 2h 30m.

Except that right now, unless you have an exemption motive (like a need for work or to care for a sick relative who doesn’t have anyone else to care for them) along with the supporting documentation, it’s illegal (under current internal Covid restrictions in place until April 6) to go from Tuscany to Liguria.