"If you look at the performance of the Port of Tauranga, it is performing very strongly within New Zealand and relative to other ports and that's why it's been building market share," he told the Bay of Plenty Times in an exclusive interview.
"It's been a significant competitive threat to Auckland and that's an example of its success and I think that should be celebrated because for Tauranga this is a part of the world that's growing fast, it needs more businesses to attract even more people and give them more reasons to be able to support their family here and the port is an integral part of that."
Port of Tauranga chief executive Mark Cairns said the wharf extension by Tauranga-based HEB Construction increased the wharf length to 770m and would allow the terminal to handle three large vessels at the same time.
Last year, the terminal handled 850,000 containers (TEUs), which was up 25 per cent on the previous year. Mr Cairns said this was expected to increase again this year, which was why dredging the shipping channel was so important.
The first stage of this project is estimated to cost about $50 million.
After the Port of Tauranga event, Mr Key spoke exclusively to the Bay of Plenty Times about the issues facing the region, such as Psa and Rena.
He acknowledged it had been "a terrible time" for kiwifruit growers and many had suffered financially and emotionally but when asked he was not aware of any new proposals to offer assistance.
Despite this, he said there was hope and the Government's $25 million contribution to developing cultivars had begun to show high levels of resistance against Psa.
When asked if Rena should be left on Astrolabe Reef or be removed, Mr Key said the wreck could be a major tourist attraction as long as the environmental impacts were mitigated and the views of locals were considered when making a decision.
He spoke favourably about the region, and said Tauranga promoted itself well and there were many people who had not experienced the region's "sheer beauty".
"I think it's a really fabulous part of New Zealand ... and it's got all the advantages of a bigger city but with a nice feel to it. It's not the hustle and bustle of Auckland but feels like a go-ahead place."
Mr Key said he enjoyed visiting Tauranga and would like to bring wife Bronagh here on holiday.
And finally, asked whether he was worried about losing his title as the country's sexiest politician to Tauranga National MP Simon Bridges, Mr Key said he would be happy to pass the mantle over.