SECRET GULLY is a beautiful small valley set in the eastern edge of the "granite country" in the Great Dividing Range of Northern New South Wales, Australia. The granite country is distinguished by massive boulders and majestic granite capped mountains and ridges. Secret Gully is surrounded by ridges and spurs rising 300 metres and more above the valley floor.

Through the heart of Secret Gully runs a dramatic waterway. Draining around 120 square kilometres of high rainfall country, the creek/river can quickly change from a sleepy chain of ponds to a pounding majestic floodway plunging through a set of twisting rapids that plummet through a steep gorge.

The valley itself was once the bed of the creek which runs through Secret Gully. But in some distant time, a mighty flood must have carved a new pathway, creating the rocky gorge, and leaving the old creek bed as a little perched valley. The old bed gradually filled up with sandy material washed from the decaying granite hills, thus creating a tiny level valley floor in the midst of endless towering granite ridges.