Any Esperance Beach (particularly out at Cape Le Grand National Park)

Kangaroo on the beach at Lucky Bay

Drive 8 hour south from Perth and you'll come across a picturesque, little coastal town called Esperance. Any one of the town beaches are spectacular, however, just out of town within the Cape Le Grande National Park you will find Lucky Bay and Cape Le Grand (photos attached)
The sand is so fine here that if you kick your heel against it, it squeaks. It is common to find kangaroos grazing up behind the dunes of Lucky Bay.

These are some of the most beautiful beaches in the world that I have seen. (and I've been to some lovely beaches eg/ Bermuda, Bay Islands of Honduras, The Yucatan Peninsular in Mexico to name a few)