Yes , gibraltar is a good area for hunting, but be careful with planes.
i decided to push the things a bit and i enter to the med with my IX-b boat in 1941 and is an interesting zone, not large convoys but yes little convoys of two ships escorted with two or one destroyer. very challenge for now.
Also i saw interesting encounters with british units and the luftwaffe near malta (stuka aerial attacks and bombings against cargo and destroyers )
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at the moment... three destroyers, three cruisers, four large troop ships, two landing ships with war material, and other little merchants. (one patrol and half)