John B.
Yelp
If you wander up and down the Australian coast, you can't lose. But if you had to pick one place that was reachable and amenable, yet wild and spectacular, you would be hard-pressed to beat the sights at Noosa. While there are settlements at the river's mouth and along most of the coast, this park in between those two areas is a relatively untouched stretch of rainforest, rocks, and beaches that scream "tropical paradise".
A trail runs along the water's edge through various small bays, paved for a stretch and then dirt and gravel. An athlete on a mission could probably run through in an hour, but there's no reason to rush, and it's quite easy to spend days here stopping at different sites each time. Separate paths run away from the water through forested areas (which don't have nearly the same views). Some of the water is swimmable (albeit unguarded), but I tend to be most engaged by the peace and quiet of water hitting sheer cliffs.
One can't guarantee any particular wildlife will show up, but you're likely to see something interesting. There are wild koalas (though they tend to be sleepy and high in trees, so you have to be sharp-eyed), but also giant lizards, tropical birds, and an array of insects that provide an interesting soundtrack but are thankfully deterred from most of the path by wind. In the water, I've seen sea cucumbers, sea turtles, a manta ray, and more. In season there are reputedly whales to be seen as well.
The weather is warm all year round, and you can drive (though parking can fill on prime vacation days) or take transit (which does take a while). Starting from the town of Noosa, you'll finish the hike with extensive views of the Sunshine Coast, needing either a ride back to the town or another walk through the park. It's not a bad problem to have.