Jewel Cave lies much closer to Augusta than to Margaret River town, but it belongs naturally to a southern Margaret River loop. It is the largest show cave in Western Australia, with high chambers, long straw stalactites, and dense crystal decoration that gives the place its name.
The cave is best paired with Cape Leeuwin Lighthouse and the southern forests rather than squeezed into a northern wine day. Tours are guided, and the underground temperature is cooler than the coast; bring a light layer if you feel the cold.