Olaf's Summer Fun

 is a limited-time decoration released with the Frozen Event Update on 7th December 2016. It could be found in a Silver Enchanted Chest.

Trivia

 * was removed from the Enchanted Chests, giving it limited-time status, with the Mulan Event Update on 26th January 2017.
 * was a Legendary Chest prize in the Frozen Legendary Chests Promotion on 28th April 2017.