The UK Foreign Office recommends against all but essential travel to Cabinda Province outside of Cabinda City.
Cabinda is an exclave region of Angola separated from the rest of the country by a strip of land belonging to the Democratic Republic of the Congo. It is not a tourist's paradise. There isn't much to see, but more importantly it is hard to get in or go anywhere because of visa and other permit restrictions. Most visitors are on business in the petro sector.
Cabinda used to be known as Portuguese Congo. The Portuguese did at times attempt to control the territory between Cabinda and the rest of their holdings in southwest Africa, which would have made things a lot more convenient for the Angolans today. But the territorial discontinuity of what would become Angola was set by the 1884 Berlin Conference, which established that Leopold of Belgium's personal property of the "Congo Free State" would extend along the Congo River to the Atlantic.
The Front for the Liberation of the Exclave of Cabinda (FLEC) has waged a secessionist struggle against the Angolan government since independence. The province's vast oil reserves, first explored by the Portuguese in the 1950s, guarantee that the Angolan government will use its powerful army to maintain tight control. Expect to see a very large military and police presence here.