I hadn't heard about the underwater Cosquer Cave until encountering this online MSN write-up: https://www.msn.com/en-us/travel/news/race-to-save-undersea-stone-age-cave-art-masterpieces/ar-AAXRLJ8?ocid=msedgntp&cvid=b01910c2671240908dd75fa09c3d6a95.
The underwater cave, discovered in 1985 by a diving instructor who (illegally) didn't report the find until 1991, was above the water level during an extended ice age and was visited over a period of 15,000 years. There are images and carvings. Experts are working frantically to finish mapping the entire cavern before rising water levels erase the art, some of which have already been lost.
A replica described as "almost life size" opens in Marseille next week.
I haven't been able to find a website for the tourist attraction, but I assume one will pop up within a few days. In the meantime, this article describes the new venue, which is located very near MUCEM on the Marseille waterfront: https://www.completefrance.com/travel/activities/grotte-cosquer-replica-opens-june-2022-marseille-8484610