Hihi, no cave in the Netherlands. But I know that Germany can be strange. With a TDI certificate you aren't allowed to dive alone in Brilon (you must hire a guide). I asked why, because iantd, gue, nacd are accepted there, but TDI not. They didn't answer. So I don't know the reason. Maybe it's the depth of 40 m. but if you have a certificate to dive deeper, whats the problem? And a normal iantd full cave is for 40m. depth too. I know a lake in Germany where only CMAS divers are allowed to dive. So I can dive there, because I have CMAS 3*, but my friend won't, because he has PADI AOW. Germany don't like Padi certificates I think (another place: padi aow: 25m. depth, cmas 2*: 40m. depth, both advanced open water diver). France only CMAS? I don't know.