We try and do the hike every time we are at Whites/Great harbour for at least two nights. Basically second what Knotthead has said. We leave at about 9ish and head up the paved road which eventually turns into more of a road for Jeeps etc. We hike over to Diamond and have lunch at Taboo and then go to the Bubbly Pool. Cab back. We have done it at least 6 times and are still can't get enough of the views. Couple hours for sure and yup, take water.