“I’m keen that divers aren’t disappointed when they arrive at the site to find that there simply isn’t a pier,” Chris Holden, author of the ebook “The Essential Underwater Guide to North Wales”, told Divernet.

Trefor Pier was built in 1870 and later extended to 100m, but when no longer used commercially it went into decline, said Holden.

Gwynedd Council had long posted signs warning that the structure was unsafe, although divers still ventured beneath it while anglers fished from above.

Despite long-running repairs and petitions urging its preservation, the cost of rebuilding was considered too high and the demolition work began this month – although, as Holden pointed out, Hurricane Ophelia might well have destroyed the fragile pier for free.

With the shallow depth, easy access, variety of marine-life and often good visibility, Trefor Pier was a popular choice for underwater photographers and new divers, said Holden.

“The wooden pillars and horizontal spars that formed the structure of the pier provided holdfasts for plumose anemones, dead men’s fingers, kelp and bootlace-weed, while the rocks and baulks of timber on the seabed provided nooks and crannies for lobsters, crabs, octopuses and eels.

“The surrounding seabed is flat sand, so the pier created an oasis where marine-life could thrive.”

Holden plans to dive to investigate the state of the seabed following the demolition, and will revise his ebook accordingly. Anyone who owns it will be able to download the amended version at no extra cost.

Divernet - The Biggest Online Resource for Scuba Divers