If you're ever in Darwin, NT, and feel like you need a place to chill, then I would highly recommend the Nightcliff foreshore.
The stretches of sand and rock pools make it ideal for a family outing with children, or just a casual picnic for two on the sand.
If you're worried about getting dirty, there are numerous benches and tables which make it very easy and convenient to have a meal without fear of getting a mouthful of sand.
There are also public barbeque facilities if you are keen on your protein. If you walk towards the end of the foreshore, you'll find you have reached the nightcliff jetty.
The scenic ocean views are world class, and if you are feeling up for it, you can try jetty jumping (though it is not official). Come evening and you're feeling peckish, there are usually some food vans that come which sell coffee, ice-cream and hot chips from Monday-Saturday.
So if you're looking for a relaxing day with beautiful views and most importantly, for free, look no further than Nightcliff foreshore (its recommended you're in the city first though).