My wife was in Jaws2. She said the hardest thing was waiting for the right conditions so the shots would match. Pre-CGI. She was shooting for almost an entire year.
Parts of the movie are shot in a freshwater lake called Ijsselmeer in Holland. In a little town called Urk. Lol. No France and no Ocean at all.
I couldn't help but notice the conditions off the beach changing dramatically too. From pounding storm surf that no boat could beach launch through to an easy paddle out. Didn't ruin the movie for me though, I thought it was great. They should have made the fleet of private boats a whole lot bigger.
I enjoy the Dunkirk, They kept a lot of tension in the whole movie. Yes the the storm surf to flat waves was problematic. Had to turn off my Surfer Brain. The ending also was off Iknew the Spitfires had a lot of glide but really.I don't think Glider would have stayed airborne for that long. One of the things that I liked was they used many of the real Boats that made the crossing to rescue the British Army from Dunkirk. Many years ago someone had the idea that those Boats should be found and restored. Kind of a living museum.
According to Mikki Dora Malibu went to the Dogs in 1964. The Chumash Indians will tell you it was 1664.