I have never been in a tunnel they runs under water, but I suppose when your in it, you really don't notice it. Good that you were not driving, and taking pics. kind of like texting and driving. :) tigs=^..^=
We have one here in the states. I-10 in Alabama between exit 26-27 runs under water where the Mobile River runs into Mobile Bay. When trucking I had to pass thru it often. Never liked it. They give me the "willies".
I believe you, when you say your good lady was driving!..☺