If you stay in Arugam Bay for a considerable amount of time you will certainly experience the “Poya”. Wikipedia describes it as: the name given to the Buddhist holiday of Uposatha in Sri Lanka, where it is a civil and bank holiday. Full moon day is normally considered as the poya day in every month.
Arugam Bay is a very popular destination for many Sinhalese who travel from all over Sri Lanka to celebrate the Poya. You can expect lots of activity on the beach during the night and many more locals swimming near Baby Point during the day. If you are travelling to Arugam Bay by public transport be aware that there will be a lot more people travelling on this day, all over Sri Lanka, so be early to avoid disappointment.
When is Poya
A list of Poya days and other public holidays in Sri Lanka can be found at this this website (opens in a new window). These are also useful to know if planning a trip to the visa office as it closes on bank holidays.
Also bear in mind that the majority of Arugam Bay residents are Muslim or Hindu so do not expect them to be celebrating!