Montgomery Reef is located off Western Australia's Kimberley coast, at the southwestern end of Camden Sound and surrounding Montgomery Islands. The reef is approx 20 km (12 mi) offshore, opposite Collier Bay (to the south) and Doubtful Bay (to the east). The nearest populated settlement is Bardi. Montgomery Reef is nearly 130 km (81 mi) to the southwest and has a total area of 400 km2 (154 mi2) making it Australia's largest inshore reef.
With a length of about 80 km (50 mi), the reef is subject to remarkable tidal movements to a maximum of 10 m (33 ft). When the tide is out sandstone islets, vast lagoons and a central mangrove isle are revealed. The outward movement of the tide forms a torrent of water, creating a river cutting through the reef and hundreds of cascading waterfalls. At low tide, more than 4 m (13 ft) of reef can be exposed.
When the tide is out-going a series of cascading waterfalls are revealed which attract migrating wading birds, manta rays, feeding turtles, dugongs and black-tipped reef sharks. The region is a popular tourist site and offers several cruise operators visiting daily.
Montgomery Reef and island are both christened by the first European to sight the isle aboard Mermaid, Philip Parker King (1791-1856), while exploring the region in 1818. He named the island after Andrew Montgomery, ship's surgeon.
Yawajaba Island (aka Montgomery Island) is located approx 22 km (14 mi) from mainland Kimberly (off-shore). The island has total area approx 2,3 km2 (o,9 mi2 / 230 hectares / 568 acres). Yawajaba actually groups three islands (located very close to each other) surrounded by the Montgomery Reef.