we have just received an invitation to go to a wedding in late July. It is at the Ulawatu Surf Villa. Can anyone please advise me of what to wear? The invitation says semi formal and bathers. Never having been to wedding in Bali before not sure of what semi formal would be. Also what would the temperature be about then? We are going in 16 days so thought that if I had an idea of what to wear I could buy something this trip.