The Cook Islands, a sovereign state in free association with New Zealand, uses two official legal tender currencies. The New Zealand Dollar circulates in parallel with the local Cook Islands Dollar; at the same time, the government also authorises many legal tender coins in the Cook Islands Dollar currency for collector's purposes. Many of them are in standard bullion sizes, including one ounce of gold - such as this coin.
This coin is part of the Numismatic Icons series by CIT Coin Invest.
The mint says about it:
For the fourth issue of the series, we get acquainted with Arethusa - a captivating nymph and companion to the moon goddess Artemis in Greek mythology. According to legend, she unknowingly bathed in a river belonging to the river god Alpheus, whom she inadvertently seduced with her beauty. Arethusa, wanting nothing of his advances, fled her home in Arcadia. Relentlessly pursued by Alpheus, she sought help from Artemis. The latter transformed the nymph into a stream under the sea, which emerges as a water fountain on the island of Ortygia in Syracuse, Sicily.
The Syracusan coins with Arethusa’s image are said to be among the most stunning of ancient Greece and regularly achieve record prices at auctions. | 
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