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Face down in a metre of freezing water somewhere up the Arrow River, Henry Geerlings knew he was on to something big.
He saw a flash of yellow, reached down, cleared some sand from a crevice and levered free a nugget of gold "the size of a flattened chook egg".
"I was standing in the middle of the river, shouting, 'no way, no way, I don't believe this is happening', and my voice was echoing back off the hills."
It was 2006 and the part-time prospector had used a mask and snorkel to find one of the biggest nuggets taken from the Arrow in 100 years.
At 8.8 ounces, it fetched $15,000 on Ebay, sold to a man in central Otago.
Today the nugget would be worth much more after the price of gold doubled in the past two years.
At more than $US1000 ($1250) an ounce, gold is once more among the hottest of commodities - and sparking a new gold rush in the South Island.
From big companies spending millions on geophysical aerial surveys to individual prospectors, people are returning to the once famous gold-mining areas of Otago and the West Coast.
"There's been quite an influx out there," said Geerlings, who was used to having the Arrow and Shotover rivers to himself.
"There's all kinds... anyone with a sense of adventure, hoping to get lucky."
Matthew Brown, acting manager of the minerals division of Crown Minerals, said he had a lot of inquiries about prospecting, "without a doubt" due to the rocketing gold price.
"We're getting more inquiries about whether certain areas are available for permitting. People are also trying to find out the historical information."
Mark Sutton, general manager of New Zealand Mint, said he too was fielding regular calls.
"Farmers in the South Island are calling twice a week saying 'there is gold in them thar hills'. They dream there is gold in their land and they want to talk about it.
"There will be more prospectors, no question."
Sutton described some prospectors he had met as "eccentric", but said "they can do very well if they strike it".
Sixteen gold fossicking areas, where people can go panning without permits, have been set aside in the South Island.
Lynn Solley from the Ross Goldfields Information Centre, on the West Coast, said she had noticed a big increase in the numbers of people wanting to use such locations.
"The gold fever is quite amazing, people are really, really excited. There's definitely going to be a resurgence in gold mining."
It's not just smallscale prospectors being lured by gold fever. Big mining companies are searching for new deposits to capitalise on the global boom.
Brown said some companies were spending millions of dollars on aerial surveys and offshore exploration.
He said there were also increasing problems with individuals mining illegally, using machines.
"It's an issue we are facing, average punters who don't know how the system works. They should know better."
Despite the increase in gold prices, Geerlings said miners still got on well up the Arrow. "I have no claim on the place. There's plenty of gold there for everyone."
Geerlings said he wouldn't call it a gold rush yet and mining was not for everyone, especially in the winter.
"I was up there sleeping in my ute... minus 10 degrees. I had to kick the tailgate open in the morning - it was frozen shut.
"Imagine what the old timers went through... a lot of them died of cold."
He said it took a bit of knowledge to learn how to read a river and work out where deposits were most likely to be found.
"You see tourists digging in the wrong place sometimes and it makes you laugh. "It's pretty naive to think you are going to get rich on gold."
But there's always a chance, and as his giant nugget proved, the old-timers didn't get them all.
"The big ones are out there," said Geerlings. "It's just a matter of finding them."
