Travel from Marseille to the Amalfi Coast

Voltea flies about 1 nonstop per week between Marseille and Naples but you'll have more nonstop options between Marseille and Rome or from Nice to Naples. Try www.skyscanner.com for your date(s).

Train travel time on the same route is 12-13 hours, my preferred schedule being the departure at 11:25 with one connection in Milan and arriving to Naples at 23:50, so you'd have to sleep there.

Try the Rome2Rio website. It gives you a lot of options. Train is just under 14 hours from Marseille to Salerno, then you have to go from there to where you are staying. Could be difficult if you are arriving late, unless you plan on using Salerno as your home in the Amalfi. You might want to add a night in somewhere if you want the train to break up your trip. Either Florence or Rome. Good luck. Seat 61 for train travel is another good site to check out.
Regards,
Tania