You can get into South Africa by three major modes - Plane, car and boat.
There is a whopping total of 10 international airports in South Africa. However, the two major ones are Cape Town International Airport and OR Tambo International Airport, Johannesburg. Flights travel on a highly frequent basis to and from Cairo, Dar es Salaam, Lusaka, Mauritius, Nairobi and more. There are direct flights here from major European areas such as London, Paris, Athens, Amsterdam, Istanbul, Zurich, Lisbon, Munich, Madrid, and Frankfurt. Apart from those, direct flights are also available from New York, Atlanta, Abu Dhabi, Dubai, Washington D.C., Doha, Mumbai, Buenos Aires, Hong Kong, Singapore and more.
If you are renting a car or arriving by taxi, you can do so from the major crossover points/borders. They are the Botswana border, Lesotho border, the Namibia border, the Mozambique border, the Swaziland border and of course, the Zimbabwe border.
Several cruise lines operate in this area, with South Africa's major cities being important stops. Princess Cruises is one such line that has Cape Town as its stop. There is also a Royal Mail Ship by the name of RMS St. Helena that halts at Cape Town on its way to St. Helena.