We went through in 79 and 80 and as a Sonarman it was a mess. Single passive contacts turning into fishing fleets and back again. Tracking 100 contacts on passive with each one doing it’s own thing. Freighters of every size going every which way. Not organized into in bound, out bound.
It is one of the most dangerous places on earth for a sub to operate. Submerged transit was the safest and with all the noise it was safe for subs to operate. The traffic and noise extended a couple miles on either side. Once through we could take advantage of thermal layers to hide, especially in the Med. Going to periscope depth at night with a hard surface layer 100 feet deep. Once in it it had a wicked sound channel. We were almost run down by a Friggen Soviet cruiser running dark ship. Bastards.
Pickets can be set up on either side if your looking for a sub of interest.
Oh yeah, the real pucker factor going through the straits submerged from possible other subs doing the same thing and all the surface noise makes subs really hard to detect other subs.
Article 20 of the United Nations Convention of the Law of the Sea states:
“Submarines and other underwater vehicles in the territorial sea, submarines and other underwater vehicles are required to navigate on the surface and to show their flag.”
Most if not all of the Straits if Gibraltar are within the territorial sea of Spain and Morocco and therefore submarines should not be transiting the straits underwater. Doesn’t mean that all states operating submarines obey this provision.
I vaguely remember reading about a tactic used by the USSR to get submarines through the Straits of Gibraltar that worked as follows. A commercial vessel sailing under a flag of convenience such as the Panamanian flag would be equipped with specialized portable electronics that are able to communicate with a submerged submarine using very very short range signals.
This communications channel was used to provide ultra precise distance between hulls information for the submarine to use to maintain a very close yet safe distance between the submerged submarine and the surface ship. The surface ship was also fitted with noise generation equipment that produced noises that were specifically modulated to mask the sound signature of the submarine that was hiding underneath the ship.
In this way the Soviet’s noisy submarines could pass undetected through choke points such as Gibraltar and others, and pass through the SOSUS sensor lines that the Soviet Intelligence agencies had managed to map the locations of.
