Whites Beach Sea Cave
This cache is not located in a National Park, however you'll have to visit one to obtain the necessary information to find it.
In 2013, Whites Beach at Broken Head was named Australia's number one secret destination in Australian Traveller magazine's "100 Incredible Travel Secrets of Australia". This effectivly blew the lid off what was once a well kept secret destination that only the locals knew about. Today the beach is popular with holiday makers and backpackers visiting the nearby town of Byron Bay.
In order to find this cache, you'll have to visit this beach. How you get there is up to you - be it a rock scramble in from the south, a more defined track from Suffolk Park, or simply get lucky and find that one of the 10 parking spots uphill from the beach is actually free. The listed coordinates of this cache point to the bottom of the stairs from the latter method of beach access.
Once on the beach, you'll want to check out the sea caves on the southern end. The cave furtherest from the ocean is deeper, and the view from inside can be seen in the photo above. Stand at the entrance of the cave, with the sheer rock face directly above you. You'll need to take a co-ordinate from this position. Bear in mind that you're at a cave entrance and that the GPS signal may take a bit to settle. Using this coordinate:
The cache is located 301m away, at a bearing of 338°
Best time to visit is low tide, you may need to wade through water at other times. The beach is not patrolled and mobile service is patchy. Your safety is your responsibility.