US ambassador's highlight was visit of the USS Sampson in aftermath of earthquake

Listening to Mark Gilbert's reflections on his time as Barack Obama's man in Wellington for the past two years sounds more like an extreme-sports challenge than a posting which oversaw the most profound bilateral relationship-repair in 30 years.

He's walked the great walks including the Routeburn, the Milford Track, the Abel Tasman and the Tongariro Crossing.

He has been to Antarctica, he has skied with the US ski team, swum with the whales, and hung out the back of an aeroplane flying at 30m over the Hauraki Gulf.

Gilbert, aged 60, has taken close to 4000 selfies and produced a slideshow on social media to the theme of "I've been everywhere man."

His own highlight, however, was more political - the visit of the USS Sampson in November, and the assistance it provided with the HMNZS Canterbury after the Kaikoura earthquake.

Banning ship visits to New Zealand was the last of the US reprisals against New Zealand's anti-nuclear laws and the Sampson was the first visit in 33 years.

"We had Vice-President Biden here, we had Secretary of State Kerry but I think having the Sampson here really tells everyone where the state of the relationship is," he said.

"To have it here, to be able to participate in the relief effort down in Kaikoura, to cement the military, the personal relationship between Kiwis and Americans, the visit puts all of that together."

It was a long slow process to get acceptance in the US system for the ship to attend the New Zealand Navy's 75th birthday celebrations.

There will be other ship visits but not necessarily regular.

Mark Gilbert

"The easiest thing for anyone to say is No and sometimes getting to Yes can be a long and difficult process," Gilbert said today.

"Once the parties understood what it meant, how it would be handled and what it meant for the relationship, we got everybody to Yes. But it took a very long time with behind the scenes discussions."

Asked if he believed it would be start of regular visits or just a one-off, Gilbert said: "I don't think it will be either. There will be other ship visits but not necessarily regular."

It was nothing to do with the relationship but was more about where ships would be travelling to.

The relationship was strong enough that no single problem could affect it.

"There could be an issue New Zealand the United States completely disagree on but it is not going to affect the relationship because the contacts on both sides have become so solid that you don't have to worry about one issue completely turning upside down the entire relationship," he said.

Gilbert, a former professional baseball player with the Chicago White Sox, was a major fundraiser for Obama, and is also a friend.

He said it was usual for the team of political appointees of a different party to end their terms on the same date as the president who appointed them - the unusual aspect of the transition was the refusal to have any extension at all.

The contacts on both sides have become so solid that you don't have to worry about one issue completely turning upside down the entire relationship.

Mark Gilbert

He didn't know if concerns about Donald Trump as President were justified.

"The jury is going to be out but hopefully he'll do a good job. Hopefully it will be great for America. I'm sure the relationship between New Zealand and the United States will continue to grow and grow in the right direction."

Gilbert said the appointment of New Zealand businessman Chris Liddell as an assistant to Trump in the White House could only help the relationship with New Zealand.

Gilbert and his wife, Nancy, have had a month of saying goodbye at functions over the country, at which Nancy has been collecting hundreds of Air NZ boarding passes for a special project back home.

She is going to decorate a wall with them in her Florida home - near Donald Trump's Mar-a-Lago in Palm Beach.

"I'm actually taking the boarding passes on my carry-on luggage," she says.

The couple will leave Auckland on Friday night after hosting a farewell function in Wellington.

Nancy Gilbert says she would remember the Kiwi character as being "kind and fun" as well as "curious."

"It might be by virtue of the location of New Zealand on the planet that when you are far from others, you develop a spirit of curiosity to see what else is going on out there and the sense of adventure to know that when someone asks you to go for a walk, five hours later you could still be walking."

A five-hour flight for New Zealanders was absolutely nothing and was a totally different mindset from most places in America.

The highlight of her time here was her own "Wahine Toa" project which recognised emerging Maori women leaders through the country and brought them together for a conference in Auckland in October.

"We bought the chief of Native American affairs from the White House, President Obama's special assistant on Native American Affairs, flew over to be the keynote speaker and it was an extraordinary experience both personally and otherwise. It was just very gratifying."