As surfers, we tend to see the coastline through two different prisms: rapid change or timeless constancy. Think about beachbreaks, they're always in flux, the banks are good today and terrible next swell. We expect them to change, even hope that they do. While reef and rock breaks are immutable, they're the same today as they were last year, last decade, and last century. We accept their permanency.

Some waves, however, don't match either category. The change is slower than beachbreaks but fast enough to perceive when closely observed, and those changes give us an idea of deeper processes at work. The Mentawai Islands are a good example. Due to their location between two tectonic plates, the Mentawais are slowly sinking and the reefs are getting deeper by a few centimetres each year.

Another wave is Skeleton Bay, and like the Mentawais it lies on a very dynamic coastline, however it isn't plate tectonics changing the shape of the Namibian coast but a steadily migrating mass of sand.

Four years ago, almost to the day, we wrote an article detailing the rapid changes happening to the shoreline at Skeleton Bay. The premise of the article was simple: “the world's most perfect and thought provoking sand-bottom left hand point break may not exist in twenty years time”.

In the subsequent four years we've had multiple satellite and aerial photograph updates, the most recent being May this year. What is evident is a further build up of sand inside Donkey Bay, where the wave runs into, reducing the peel angle and speeding up what is already a challenging and super fast wave.

At Swellnet we looked at past satellite imagery of Donkey Bay and from 1973 through to 2012 the shoreline shifted 1km north. In the four years since, fresh satellite imagery has shown the wave shifting a further 120m to 150m further north, depending on where you measure the bank from.

Overlayed satellite imagery showing the shift in coastline from July 2009 to May 2016

The Namibian coast is in constant change due to strong persistent south-southeast winds blowing off the Namib Desert, transporting sand into the nearshore zone. This along with significant longshore drift - approximately 1 million cubic metres of sand reaches Donkey Bay every year, twice as much sand as passes the Superbank - makes for a coastline in considerable flux.

"It's always changing," says Shaun Loubser from nearby Swakopmund who first rode it in 2002. "My opinion is, yes, the wave has changed since I started surfing it, but every year the banks are different to the year before." However, Shaun cautions against relying too much on the satellite passes as the sand can move a great deal: "What time of the year the photo was taken? Was the photo taken during swell, before a swell or just after a swell? All these factors will have an influence on what the sand bank is looking like from sky at that specific time."

Another regular visitor to Skeleton Bay is photographer Alan van Gysen. He's travelled there many times since Surfing Magazine blew it open in 2008, including two trips this year. "I am very concerned and aware of a big bulge of sand midway down the point that is breaking up the point and a soccer field-sized deposit down near the bottom of the wave which on a more southerly direction is creating a closeout and/or righthander! Without a doubt it's a very different wave from 2008."

A critical aspect of the wave, in fact a critical aspect of any wave, is its 'peel angle'. The peel angle is the angle between the refracted swell line and the lined traced by the whitewater as the breaking curl peels along the coast. In our Coastal Creationism articles Chris Buyx described the peel angle of waves. Most surfers want a peel angle between 50 degrees - which provides slow but fun waves - to 30 degrees - which describes fast, down the line waves.

Slight reduction in 'peel angle' from 2009 to 2016, making the wave slightly faster

In 2008 the peel angle of Skeleton Bay was approximately 25 degrees, creating fast, challenging waves that could only be ridden by advanced surfers.

Since then the coast has shifted slightly more anti-clockwise, reducing the peel angle along some sections of the wave to below 25 degrees. This is getting close to being unmakable even by the best surfers on the planet, and if a further shift is seen, we may see Skeleton Bay turn into a glorified close-out - albeit one of the best closeouts in the world.

With the wave shifting hundreds of metres north in only four years, along with the coastline steadily rotating to create a faster, less makable wave, the question is how much longer will Skeleton Bay resemeble its current incarnation. How much change can it cope with before it becomes just another bend in the coast?

The other unknown is the lagoon which abuts the point. During big swells the waves can threaten to wash into the lagoon which would change the sandflow at the bottom of the point as the runoff would need to find an outlet. Both Shaun and Alan agree that if it were to happen it'd be very bad news for the wave.

While all of this may sound horribly pessimistic there is a very bright side to consider. Before the year 2000 Skeleton Bay barely resembled the wave we know now. It was transformed into something truly magnificent by the slowly migrating sand. So just as the coast at Skeleton Bay changed for the better, so too can other waves transform from ugly ducklings to beautiful swans - even beautiful Donkeys! - when the sand falls in just the right way. To plagiarise an all-too-familiar ad campaign, the search is endless. //CRAIG BROKENSHA and STU NETTLE