Port of Tauranga chief executive Mark Cairns is a modest man considering he's played a major role in turning the company into New Zealand's largest international cargo hub.

Mark this week announced he will retire as CEO at the end of the 2021 financial year.

The port's transformation from a relatively small regional forestry one into the largest port in the country has been the stand out highlight of his tenure.

His modesty aside, the fact remains Mark has led the Port of Tauranga though a period of huge growth since he took up the CEO reins in 2005.

It's now one of the country's most successful listed companies with its market capitalisation increasing seven-fold from $665 million to $5.1 billion under his watch.

The port handled 12.6 million tonnes of cargo in 2005. In the year to June 2020 that figure was 24.8 million.

Mark says he inherited a business that already 'had great bones” but does admit the decision in 2007 to expand took courage.

'I'm a bit critical in that I think capital discipline is often lacking in the port sector.

'At that time our market capitalisation was around $2 billion so to make a $350 million investment was quite a commercial risk.”

From the week the port finished dredging it had big, 10,000-container-sized ships calling on a weekly basis, Mark says.

A lot of analysts were critical of the venture saying it was going to be another 'build it and hope they come” exercise but the port did deals with its largest customers to ensure there was sufficient cargo to justify the vessels calling, Mark says.

'There were lots of moving parts to that deal but that, when I look back on my 15 years, is the biggest highlight.”

Not only reluctant to let the successes of the port be personalised to himself, Mark can't say enough about his team and port staff who also supported him through the tough times.

'The Rena's probably the most challenging thing I had to deal with. Despite the ship hitting a reef not even on our radar range, 15 miles off the coast, I think a lot of people in Tauranga blamed the port for that so that was a really difficult time for me personally,” Mark says.

And what did he learn as a CEO from that rough period?

'The resilience of our people – they got me through that. Not vice versa. It just required a herculean effort to keep the port open when we had containers floating around in the sea and that dreadful oil spill.

'And I'm a mad keen fisherman and diver so the pollution was dreadful.”

A career in management wasn't always on Mark's radar.

As a youngster he considered becoming a doctor before deciding on a degree in engineering.

He says he was lucky to have some early opportunities to move out of the design phase of engineering and into the contracting side.

'Very quickly I learnt that I got more out of working with people than being an engineer and designing bridges.

So he shifted his second degree into management and hasn't look back.

He was named Chief Executive of the Year in the 2012 Deloitte Top 200 Business Awards, and last year won the Caldwell Partners Leadership Award in the Institute of Finance Professionals Awards.

The accolades are not something he's entirely comfortable with.

'I struggle with it in that it's not about me. I think I've said before that chief executives need to remember that they've got two eyes, two ears and one mouth, and they should use them in that proportion.

'I'm not the reason this place [the port] has been as successful as it is. It's about the quality of the people that we've got here.

In fact it's the comments and praise from colleagues since he announced his retirement this week that have meant the most.

As for what the future holds, Mark is looking forward to dropping down a gear.

'Being a chief executive is demanding, it's a 24/7 role. The phone always has to be on and when it goes in the middle of the night it's not normally a call you want to be taking. It's a high pressure job.

'Boating and fishing is my stress relief. There's something about when you cast off the lines on the boat that you leave your stresses on the shore so that's an important thing.

'I've consciously decided that there's no more executive gigs for me,” Mark says.

Business has been good to me and I'll just try and put a bit back into it now in the form of governance roles, he says.

He's already on the board of Meridian, another of the country's largest listed companies, and there are a few other options in the wings.

As far as his success goes, Marks says having an understanding of emotional intelligence, and its role in business, has been key to his career.

His advice to those starting out in management is: 'Listen to your staff. Listen your customers. Listen to your stakeholders. Don't over complicate things. Keep it simple.”