What happens
Saraswati falls on the last day of the 210-day Pawukon cycle and honours Dewi Saraswati, goddess of knowledge. Books, palm-leaf manuscripts and even computers are set aside from the morning and given offerings. Schools hold group prayers, so you will see students in kebaya and udeng everywhere.
Impact on your trip
Almost none. Attractions, restaurants and hotels operate normally. What changes is the atmosphere: far more traditional dress on the street and fresh offerings outside every shop.
What you can do
This is one of the most photogenic days in Bali with zero disruption to your plans. To see the ceremony, visit a village temple between 7am and 10am, wear a sarong and sash, and never stand higher than people who are praying.