How to get from Florence to Arles France.

Rome2Rio.com suggests that the fastest way would be to fly from Florence to Marseille then take the train to Arles, but one would have to investigate each of those legs separately to see how the times line up.

I'd use skyscanner.com for the flight and SNCF for the train. I don't know whether you'll find any nonstop flights on that route. Don't forget to factor in the cost of getting from the Marseille airport to the train station, possibly in a hurry.

Have you tried on DB Bahn?
Here is one option:

FR 9500 Direction: Milano Centrale
Firenze S.M.N. dep 06:53

Milano Centrale arr 08:40

FR 9600 Direction: Torino Porta Nuova
Milano Centrale dep 09:05

Torino Porta Susa arr 09:52

TGV 9244 Direction: Paris Gare de Lyon
Torino Porta Susa dep 10:11

Chambery-Challes-E arr 12:50

TER17525/TER17524 Train Express Regional Direction: Valence Ville
Runs as TER17525 up to Montmelian, then as TER17524, then as TER17525
Chambery-Challes-E dep 13:40 T
Valence Ville arr 15:44

TER17721 Train Express Regional Direction: Marseille-St-Charles
Valence Ville dep 16:29
Arles arr 17:59

I know, it's a long 11 - 12 plus hours journey by train with multiple changes. I wish there were flights to Marseille from Florence or Pisa (or even from Bologna), but there aren't. The closest flights would be from Rome (with Alitalia, Ryanair, Vueling) to Marseille, then the train from Marseilles. To fly from Florence you'd need to fly to Paris first (or some other European hub).

I had a similar problem getting from Bologna to Montpellier. The solution was to take a HOP flight (Air France low cost airline) from Bologna to Lyon, and then on by TGV to Montpellier. I see that HOP do fly from Florence to Lyon, so you could do similarly. From Lyon to Arles takes about 2 1/2 - 3 hours, either direct or changing at Marseille. In Lyon it seems there's a frequent bus connection between the airport and Lyon Part-Dieu station.

ETA: The HOP Florence to Lyon flight seems to be only on Fridays, but then on from Lyon to Marseille (very likely the same aircraft) after a 55 minute turnaround.

FR 9512
Dep 10:00 FIRENZE S.M.N. (Italy)
Arr 11:40 MILANO CENTRALE (Italy)
EC 34
Dep 12:23 MILANO CENTRALE (Italy)
Arr 16:21 GENEVE (Switzerland)
TER96646
Dep 16:42 GENEVE (Switzerland)
Arr 20:16 VALENCE VILLE (France)
TER17729
Dep 20:29 VALENCE VILLE (France)
Arr 21:59 ARLES (France)

FR 9508
Dep 09:00 FIRENZE S.M.N. (Italy)
Arr 10:40 MILANO CENTRALE (Italy)
EC 143
Dep 11:10 MILANO CENTRALE (Italy)
Arr 16:00 NICE VILLE (France)
TGV 6806
Dep 17:25 NICE VILLE (France)
Arr 20:02 MARSEILLE ST CHARLES (France)
TER79526
Dep 20:32 MARSEILLE ST CHARLES (France)
Arr 21:39 ARLES (France)

Using momondo.com and assuming you're travling in May there is a 3-hours flight on Vueling (that includes the connection time in Barcelona) from Florence to Marseilles.

Thank you so much. You have given me access to train info I did not have. I want to travel during the day to see the scenery and because I am to old to be changing trains in the middle of the night. All previous info indicated a long overnight train ride.

The Deutsche Bahn website provides schedules for most of the trains in Europe, though I know it doesn't cover some of the local trains in Spain. It's very easy to use. To check prices and buy tickets you then need to go to the website of the appropriate rail company.