25 Dollars - Elizabeth II 4th Portrait - UNESCO Great Barrier Reef - Gold Bullion Coin

The Great Barrier Reef was inscribed on the UNESCO World Heritage List in 1981, one of the first sites added when the program was still establishing its credibility. By 2015, the reef was already the subject of serious governmental and scientific dispute — the Australian government had spent years lobbying UNESCO to keep the site off the "In Danger" list, a designation that would have carried significant diplomatic and economic consequences. The coin arrived in that charged atmosphere.

The fourth portrait of Elizabeth II, by Ian Rank-Broadley, had been in use on Australian coinage since 1999.