Litchfield National Park would definitely have to be one of the must see places of the NT. It is located approximately 1 ½ hours from Darwin.
Now depending on who you ask, lots of people will tell you it's safe to swim in the Territory. I can tell you having lived there as a local, it is not. You take a risk in any waterway you enter with the potential of a crocodile being there. In saying that, there are "recommended" areas where the waters have been surveyed for any crocodile activity before being opened to the public. One of these areas is Florence Falls.
Florence Falls is a spectacular waterfall measuring around 25 metres high. It cascades into a lagoon that is approximately the size of a couple of olympic swimming pools with varying depths. You can view the waterfall from a viewing platform at the end of the carpark or proceed down the 160 steps for a closer look or a dip in the refreshing water.
This place is the local swimming pool during the dry season for the tourists, so don't expect peace and tranquillity. Many bring down their picnics complete with pool toys and floaties. You will find the occasional brave (or stupid) person leaping from the top of the waterfall. I do not recommend doing this though.
The lagoon is filled with large smooth rocks and black fish. Take heed - if you have ANY sores on your body these fish will be immediately attracted to them and their bite feels a bit like an electric shock!
Once you are down the steps, you can choose to continue along on one of several walking paths. The main one wraps around the back of the waterfall and brings you back to the carpark. I must suggest doing this. The other areas of little creek are very pretty and the steady gradual incline definitely beats trying to climb those stairs back up again in your thongs and togs. In terms of how hard this is, I would say you could be slightly below average fitness and still complete the path without too much trouble.
A couple of things to consider when venturing out to Litchfield: It is an offence to take alcohol into the park.
Take plenty of water, you will need it! Slip! Slop! Slap! Take a decent camera with a good zoom lens.
Take swimmers even if you think you wont swim. You may change your mind once you are there.
-No pets are allowed in the park.
-Take notice of any warning signs including crocodiles, snakes and flash flooding risks.
I lived in the NT and was a local at the park great place to go for a swim without the fear of crocs, and yes thoses stupid people jumping from the top of falls were mostly locals and knew where to jump safe of any hidden rock! Again great place for a chillaxing weekend camping trip or just a day trip after a big night in town!