July is supposed to be one of the best times to Visit Darwin.
Make sure that you make it out to Litchfield National Park and do the Croc Jumping Boat Cruise.
Also, spend a few days exploring Kakadu National Park - take a boat ride in the Corroboree billabong to see all the lotuses in bloom, swim at the bottom of the numerous waterfalls, and don't miss the 360 degree lookout point.
In Darwin, you can cage dive with crocs at Crocosaurus Cove, catch a movie at the outdoor Deckchair Cinema, or head over to the Mindil Beach markets on Thursday and Sunday nights.
It is definitely worth the trip! about 10 years ago