How do you say have a great time in Fiji?

Fiji is an English speaking nation. If you're referring to say the above in Fijian then it would be like this:-

"Qai marautaka na veivakalasai mai Viti."

Pronounced:- Nga-e-mah/raa/u/tar/car-nah/vay/vah/car/lar/sigh-my/v/tee.