When you're not sporting your wetsuit, feel free to embrace the region's casual seaside disposition by wearing loose, comfortable clothing (and don't forget the SPF!). While you won't have to worry about a language barrier here (English is the primary language) or differences in gratuity expectations (10 to 15 percent is acceptable), there are a few key characteristics to keep in mind: The official currency is the Australian dollar (AUD), which is roughly equivalent to the U.S. dollar (USD). And when driving on the mainland, remember that Aussies drive on the left side of the road.