Here’s a young working-type golden with a very nice wavy coat:
To see the advantageous of this coat, please read Rawdon Lee’s comments on utility of the wavy coat for a land-based retriever.
The other working coat for a golden retriever is flat, but it should be dense and hard to provide the same protection.
Both coats have a dense undercoat and very active oil glands in the skin to keep the water from chilling the dogs when they swim. That is a very useful feature for a dog that needs to be comfortable in the water for a long time.
I happen to like the true wavy coat a little more than the flat-coat, just because I think it provides a little bit more protection. (Miley is a moderately wavy-coated golden, in case you were wondering.)
I was recently sent a study that compared the condition of the skin of different dog breeds. The only retriever in the study was a Labrador, and Labradors had thicker and more hydrated skin than the other breeds by a very significant margin. Now, this study should have compared Labradors with other breed of their size (beagles, fox and Manchester terriers are hardly fair comparisons to Labradors).
If the study had includedsome other large dogs, my guess is the results would be somewhat different, but I do not doubt that Labradors have unusually thick skin. Thick skin does insulate the dog in the water much more effectively. It also keeps the thorns from cutting up the dog as it tears through the undergrowth.
From family lore, I have heard that the smooth dachshund that was also a great hunting dog was even more prone to being cut up in the brambles than the beagles were. That goes a long way to explaining the desire of the Germans to breed wire-haired and long-haired dachshunds as their main working dogs. One very rarely sees a smooth dachshund hunting in Europe. Most working dachshunds are wire-haired.
I do know that having been around both beagles and golden retrievers that have run over the same thorny ground, that the goldens never were as hacked up in the undergrowth as the beagles were. Of course, goldens have a much thicker coat, and the Norwegian elkhound I knew very well also never got so severely cut up in the briers and multiflora rose bushes. How much the elkhound and golden retriever strength in heavy cover was the result of having thick skin and how much was the result of having a thicker coat are questions that I cannot answer.
These comparisons of dog skin anatomy need to be explored more fully, but they are pretty interesting. We know that the average dog has thicker skin than virtually all of wild dog species. The only exception appears to be the sighthounds, which are notoriously thin-skinned, and they get cut relatively easily.
I am amazed at how much this dog resembles the golden in this Reuben Ward Binks painting: