Around 2km northwest of the piazza lies Fasiladas’ Bath, which has been attributed to both Fasiladas and Iyasu I. The large rectangular pool is overlooked by a charming building, thought by some to be a vacation home. It’s a beautiful and peaceful spot, where snakelike tree roots digest sections of the stone walls. You must obtain your ticket at the Royal Enclosure before visiting Fasiladas’ Bath.
Although the complex was used for swimming (royalty used to don inflated goat-skin life jackets for their refreshing dips!), it was likely to have been constructed for religious celebrations, the likes of which still go on today. Once a year, it’s filled with water for the Timkat celebration. After the water is blessed by the bishop, the pool becomes a riot of splashing water, shouts and laughter as a crowd of hundreds jumps in. The ceremony replicates Christ’s baptism in the Jordan River and is seen as an important renewal of faith.
Source: Fasiladas' Bath | Gonder, Ethiopia Attractions - Lonely Planet