In its enormity, it is not astonishing to find hidden treasures or swimming holes scattered through the national park. Some places are not even in the tourist map of Kakadu and only known to the guides and park rangers. Some of these hidden swimming paradises are not visited by crocodiles as they don’t really like having to climb across rocks.
Though the most popular swimming places are frequently checked by the rangers to make sure ‘salties’ are not hidding in the depths and make it to the news covers by attacking a distracted tourist. To search and dispose of crocs, the rangers use a few different methods. They might put a cage in the water with a feral pig’s leg at the end with a simple pull and close the hatch mechanism and trap the crocodile inside. Another way to check if estuarine crocodiles are about is by putting a styrofoam ball in the water. Crocodiles, being the inquisitive animals they are, will bite the foreign object. Rangers can then look at the teeth marks and determine if they are salt or fresh water crocodiles.
Rangers also use the good old have a look and see for tracks of animals method.
Lastly, at night, rangers flash lights along water surfaces. The crocodiles eyes will be easily spotted as red reflections in the water, much like humans eyes on a night photo taken with a flash.
In any case, all these methods are not certain and you can always be risking your life if you do decide to have a swim. Though if you come out, you might have a good story to tell. And feeling refreshed from swimmingin the crystal clear waters.