Cassis

Pkatz,
I've not been to Cassis, but according to http://www.rome2rio.com, it will take you a bit over an hour (each way) to travel from Marseille to Cassis.

One of your options, although expensive, would be to take a taxi (24 minutes each way without traffic).

You don't say if your cruise ends in Marseille or it just stops at the port for the day.

If this is not your final destination, then you'd need to figure out if it's worth your while to travel to Cassis.

Having been on a cruise before, I know that it takes longer than you'd expect to disembark.

Make sure you embark before the departure time as you wouldn't want to be left behind ;-)

Enjoy your cruise!

Priscilla

Without knowing how long you have, it's hard to say. There is a local bus that picks up at various stops in Marseille. Also, there are trains, but not only do you have to get to the Marseille station, but you also have a 4 kilometer walk from the Cassis station up near the vineyards to the town and port below. Probably the best is to look for and hire your own excursion and get others on the ship to join you, or check your roll call on Cruise Critic to see if someone else has organized something. Or the taxi.

The worst connection is between the Cassis train station and the waterfront. There's a local bus that just runs once an hour. I'd take a taxi to the waterfront from the station, and if you want to save money, check on the schedule and plan to take the bus back. Cassis is charming without all the glitz and ridiculous prices of Riviera beach towns.

If you want to focus on the Calenques instead of the town, a scenic excursion boat gives you the best view , closer than your cruise ship would be able to get, but does not drop you in Cassis.

FYI, good video here of taking the train from Marseille to Cassis: https://www.youtube.com/watch?v=TfGoHN7cyk4
It always helps me to see something in action!