Hello again,
Thanks a lot for your reply.
The article I am talking about is just a vulgarisation article about bioluminescence (my research topic), and no precise details about the U-34 are given.
The author claims however (without providing his sources) that the U-34 was detected (and sunk) due to the light emitted by the "disturbed" bioluminescent organisms in the water.
In "the bioluminescence world", the submarines are always given as "hating" bioluminescent seas as this could provide their position.
It is also always declared that both the American and French navy are investing a lot of money to find ways to avoid eliciting bioluminescence.
But for both these "assertions", I cannot find any sure source thus far.
So if someone knows more about it, I would be very happy to hear it.
Thanks again
Marcel K.