One of the 10 U-boat pens at the La Rochelle U-boat bunker.
This was a really impressive place to explore, the scale is something to be seen. And with a concrete roof at around 7m thick it is virtually indestructible.
The Egyptians left the pyramids, the Romans left the Colosseum, we are going to leave a submarine bunker.
There is a report and more photos from this location on the exploration blog.