Disclaimer: I am not 100% sure.

I think the immatriculations of the boat is TO 297 or TO 291.

As others said TO means the boat was originally attached to the port of Toulon, in Provence, France or in the same maritime county.

The architecture is typical for “pre-concrete” French Riviera.

Also the two haul sailer might be a famous ship : The Zecca. Here is a picture of it, one can recognise the two haul and the proue. —Please do archive this image as it should disappear from eBay— .The eBay picture (Idea from /u/Saint_eX, kudos also for him. I disagree with some of his conclusions in /r/France especially about the localisation of Zacca, if Flynn lived in La Seyne sur Mer it does not means that his yacht must have been in this port especially as it could have been exposed to bombings. And both cities he’s house was only at ~8 km from the Quai du Levant.)

The wind on the marine (like) nazi flag indicate a east to west wind and so it is at least an half open bay, also as camera used a long exposure time then, it means that flag where not constantly moving during the lapse time of the shoot. It indicates that there are no huge obstacles on the east of this pictures. However because of the Mistral wind regime it should not be a too determining factor.

This picture might be the most useful : WWII+-+Blurred+Photo.jpeg : the specifics angles of the wall in the upper quay made me think that it could be in Sanary sur Mer, near Quai Marie Esmenard. Sanary-sur-Mer is a coastal village on the west of Toulon and in the same maritime county that Toulon. A plausible indice of something to link with allies is that soon after the war a part of the quay was named “Quai Wilson”.

Hence your main picture was certainly shoot in the “Quai du Levant”.

Sincerely, A Frenchman.

It does look like the Mediterranean coast. Looks a little like Toulon but the hills are I think too low. If no one stops by here, who knows it, You might try posting it on r/France to see if anyone recognizes it.

Excellent information. Thanks so much.