I've learned that Virgin Blue will take 5 kilos of Sporting Equipment free of charge, above your 23 kilos of allowed checked baggage. Some airlines don't consider dive kit to be sporting equipment. Is Virgin Blue one of them?
https://www.virginblueairpass.com/Helpme/FAQs/questions/73/Can+I+take+my+sporting+equipment?
https://www.virginblueairpass.com/Helpme/FAQs/questions/73/Can+I+take+my+sporting+equipment?