Having said that, I wasn't massively looking forward to re-reading Peter Duck, which is one of two books in the series (the other is the deeply problematic Missee Lee, which interestingly was absent from my Christmas set and had to be bought years later) which isn't a 'real life' adventure, but as Swallowdale makes clear, is made up over Christmas holidays by the Swallows and Amazons themselves, with assistance from Captain Flint -- a story within a story, with Peter Duck himself a fictional character invented by the children (meta, eh?).
However, I was surprised by how much I enjoyed this book! Yes, it's a fantastical adventure involving a race for pirate treasure, water spouts, stormy seas, a hurricane, some pretty scary violence and some racist language, but it retains the realist, believable atmosphere of the other more mundane adventures, with lots of practical detail about sailing (maybe too much detail for some), stores and sewing. (Though the one detail missing from the floor plan of the ship is the toilet...)
I noticed this time through that the nasty villains (one of whom is a 'big Negro,' oh dear) take out all their violence on Peter Duck and the rescued cabin boy Bill, so none of our regular protagonists suffer any injury. If it wasn't for the aforementioned racist language, which honestly I think could be edited out without much trouble this time) this is a cracking adventure story with a satisfying conclusion.
ETA: Forgot to add that Captain Flint was dozing when he had Peter Duck tell the story of Pelorus Jack, the welcoming dolphin, who was indeed real, but lived in New Zealand rather than Sydney Harbour.