Not all tourists... some are 'scientists' retracing the Mawson expedition's trail and hoping to show how badly the southern ice cap has melted since then. Apparently the melting is pretty bad since they managed to get not one but two ice breakers frozen in ice in the middle of the Antarctic summer

They left from an Australian port but then I imagine a lot of ships heading towards the Antarctic probably do. In fact the US ice breaker on the way to save the other two left from an Australian port after taking on supplies.