While staying near Walpole on the south coast of WA (blog post), when we asked locals about swimming and snorkelling beaches in the area the unanimous answer was Greens Pool. On arrival, it was easy to see why.
“Greens Pool lies on the edge of William Bay National Park and is famous for its turquoise green waters and pristine white sandy beach. Large granite boulders surround the pool, protecting it from the might of the Southern Ocean.” Parks and Wildlife Service
