The Holidinghy is a free ship for the Holidays! Players are given the ship and then can upgrade it by completing the Tree of Gifts quests that appear each day.
The quest appears each day and the tree can be harvested every 24 hours. Be careful not to collect from the tree until the quest appears so you will get your tinsel!
Don't worry if you miss a collection or two, you'll still have the opportunity to completely upgrade the dinghy at the end of the quest.