There is a tradition in Denmark to issue commemorative coins to mark special events in the royal family – e.g. accession to the throne, jubilee, wedding, silver and gold wedding anniversary, and special birthdays. As for ordinary 10- and 20-krone coins, the commemorative coins bear a portrait of the monarch on the obverse, but usually a different portrait to that used on the ordinary coins in circulation. All the coins are legal tender and can be exchanged at face value at Danmarks Nationalbank.
The thematic coins were issued as ordinary 20-krone coins in circulation. Past themes have been Towers (tower coins), Hans Christian Andersen´s Fairy Tales (fairy tale coins), the International Polar Year (polar coins), Ships (ship coins) and the series with Danish scientists theories (scientist coins). Read more on Danmarks Nationalbank's website.