patrols based out of Holy Loch, Scotland, that involved clandestine courses that required passage through the Straits of Gibraltar, Mediterranean Sea, Dardanelles, and Bosphorus. Each of these accomplishments was achieved submerged [...] The Bosphorus passage was particularly treacherous and irregular, with complex positioning and course changes that were affected by currents and the presence of Soviet submarine traffic and planned impediments.
(We ignore that the map shows a route straight through Perekop isthmus. The Bosphorus is what interests us here.)
The reference to "Soviet submarine traffic" seems to suggest this was not regulated traffic. The Montreux convention says that "submarines must travel by day and on the surface". On the other hand, surely NATO/Turkey would have been able to detect submarines in the Bosphorus in 1969?
Am not sure it would have been practical to do it with the technology available in WW 1/2.
So the question is: are there any records of any submarines not friendly to Turkey passing through the Bosphorus submerged?