Ubon Ratchathani Candle Festival

The Ubon Ratchathani Candle Festival (Thai: งานประเพณีแห่เทียนเข้าพรรษาอุบลราชธานี), the most elaborate of the traditional parading of candles to wats (Thai: แห่เทียน, romanized: hae thian), is held in Ubon Ratchathani, Isan, Thailand, around the days of Asanha Puja (which commemorates Lord Buddha's first sermon) and Wan Kao Pansa (which marks the beginning of vassa). At the start of the Lenten period, it is traditional in preparation for the rainy season for the devout to donate to items for the personal use of monks, and of candles to dispel gloom in their quarters and elsewhere within the wat.

Source: Wikipedia — Ubon Ratchathani Candle Festival (CC BY-SA 4.0)