What happens to my itinerary on Sri Lankan full moon (Poya) days?

On Poya days, your usual travel plan stays pretty much intact, but you need to expect strict limitations on alcohol sales throughout the country and also the closing of some meat-serving spots. Heritage places end up way more crowded too, mainly with local pilgrims.

Poya days are public holidays in Sri Lanka; they celebrate major Buddhist observances. Hotels and supermarkets will not sell alcohol, yet a few tourists still drink duty-free liquor quietly in their rooms, maybe even without much discussion. Your chauffeur-guide will probably rearrange the schedule for temple visits so you can dodge the thickest crowds, or they might do the opposite, to let you observe the energetic religious ceremonies.