Time and tide are rapidly changing one of Nelson city's most valued natural assets.
The shifting sands at Tahunanui Beach are once more challenging the council to find a solution to halting the erosion, and are leaving locals wondering what sort of beach they might soon be left with.
The beach, just minutes from central Nelson, is worth millions of dollars in tourism revenue each year, according to the city council's deputy mayor Paul Matheson.
"In terms of importance to Nelson it's ranked right at the top, because it's the gateway to the city itself."
To those who enjoy an evening stroll, swim or paddle in the warm and gentle seas of Tahunanui Beach, the experience is priceless.
Ocean kayaker Belinda Heaphy said it was an "amazingly important beach", but it was moving all the time.
"That's a natural thing and rather than work against nature, we need to work with nature and we're slow at learning that."
Young Nelsonian Tiaki Sharp said the beach was a really important part of his family and the community. He understood the beach was at risk from erosion.
"That would just ruin something a lot of families here live for."
Ocean and estuary currents, plus increasing storms from the north, are taking their toll. They are shifting the sands back to where they were nearly 150 years ago.
Mr Matheson has lived close by for more than 30 years and has watched the beach change. He said the problem was not so much the beach, but the things built on or near it, such as the Tahuna Beach Holiday Park, which could accommodate 3000 campers.
The Nelson Golf Club and Nelson Airport right next door are also bounded by the sea that is nibbling away at their edges.
Holiday park manager Marcel Fekkes said there had been noticeable change in the two years he has been there.
"We've seen quite a bit of change where there was a sandspit with some growth on it, and the sea has changed things around. That sandspit's now gone and we're backing straight on to Tasman Bay now."
Mr Fekkes reckoned a specially built rock wall built near the camp some time ago was doing a good job of slowing the erosion. Mr Matheson said the council has included erosion control in a wider management plan for Tahunanui Beach and Reserve.
Erosion control 'a delicate balance'
Nelson geologist Mike Johnston said mitigation was a delicate balance of making sure that fixing one problem did not create another. He said two large sandspits being pushed further out to sea past the beach could soon collapse.
"Doing any engineering works around the beach could precipitate the collapse of those two big spits that go well out almost opposite Haulashore Island [opposite Rocks Rd on the the Nelson waterfront]. They're going to collapse sooner or later which is going to shift a lot of sand," Dr Johnston said.
Another Nelson geologist, Murray McClintock, said any beach, reef or sandspit was a dynamic environment, but the biggest concern was whether things were changing faster than they were.
"One of the big overprints we're going to see in all coastal environments is the impact of sea level rise - that's already happening and will continue to accelerate. We need to ask ourselves, 'what are we trying to preserve?'
"We may be trying to hold back sea level change," Mr McClintock said.