When there was trouble in The Middle East between Israel and Egypt in 1973 , almost all shipping was rerouted via the Cape of Good Hope. As it is , there are VLCC that are too big to go via Suez and have to be routed via the Cape. So it straddles one of the most important shipping routes in the world.I personally don’t think South Africa spends enough on its Navy…it always comes third after the Army and Airforce.Submarines are also a relatively “stealthy” force multiplier and thus make perfect sense for a smaller navy ….