Timkat is the Ethiopian Orthodox celebration of Epiphany. It is celebrated on January 19 (or 20 on Leap Year), following the Ethiopian calendar.
This festival is best known for its ritual celebration of the act of baptism; early European visitors confused the activies with the actual act of baptism, and erroneously used this as one example of alleged religious error. In fact, after a mass is said near a stream or pool late at night (around 2 a.m.), the nearby water is blessed towards dawn and sprinkled on the participants, some of whom also bathe in the water. But the festival does not end there; Donald Levine describes a typical celebration of the early 1960s:
By noon on Timqat Day a large crowd has assembled at the ritual site, those who went home for a little sleep having returned, and the holy ark is escorted back to its church in colorful procession. The clergy, bearing robes and umbrellas of many hues, perform rollicking dances and songs; the elders march solemnly with their weapons, attended by middle-ages men singing a long-drawn, low-pitched haaa hooo; and the children run about with sticks and games. Dressed up in their finest, the women chatter excitedly on their one real day of freedom in the year. The young braves leap up and down in spirited dances, tirelessly repeating rhythmic songs. When the holy ark has been safely restored to its dwelling-place, everyone goes home for festing.
Information based on http://en.wikipedia.org/wiki/Timkat