Arthur Ransome, who died in 1967 at the age of 83, was an old-fashioned kind of man who wrote stories about children having adventures during their school holidays in the 1930s.
The attraction is that, at his best, he was an excellent storyteller whose books hold interest for adults as well as children.
Although he used various different locations, his most characteristic books were set in the Lake District, where he took holidays himself as a child.
The characters are mostly keen on sailing, and there's quite a bit of talk about boats, but not enough to interfere with the story.
It's somewhat interesting in the context of the 1930s that his children and their families seem to have been as godless as I am: I don't think the subject of religion ever arises, and no-one goes to church. More typically for fiction of that period, they all had stomachs of 100% efficiency: despite the well-documented consumption of food and drink, bathrooms don't seem to exist, and they never need to retire into the bushes or dig latrines when camping.
The novels
Swallows and Amazons 
(1930) (last read 2011).
This book is generally regarded with affection because it's the first of the series;
but the children are at their youngest
and the book mainly serves to introduce the characters and the situation.
Nothing much happens in the first seven chapters;
after that, things begin to happen, and there is a coherent plot,
but the excitement level is not high.
You can enjoy this book as a pleasant gentle read, if you don't expect too much.
Swallowdale 
(1931) (last read 2011).
An amiable but unmemorable book, in which the excitement level is again relatively low.
It consists of a series of little anecdotes strung together without any consistent theme.
Worth reading for completeness if you've read others in the series and want more;
but, if you picked this one up without having read the others,
you might not manage to finish it.
First appearance of the dreaded Great Aunt Maria.
Peter Duck (1932) (last read 2011).
The Swallows and Amazons sail in a yacht with Uncle Jim and an old seaman called Peter Duck
all the way to a Caribbean island to search for buried treasure.
They're menaced and attacked by adult criminals in another yacht called Viper,
also after the treasure, and Uncle Jim is nearly caught by a shark.
This is a fantasy story: we're not supposed to believe that it really happened
in the context of the other books. But it's told straight and makes quite a good story,
although Ransome makes sure that none of his regular characters comes to any harm.
Winter holiday 
(1933) (last read 2011).
One of my favourites, an exciting quest-style story with no baddies,
in which the only hazards are the weather, illness, and faulty communication;
but they turn out to be quite sufficient.
First appearance of Dick and Dorothea.
Coot Club (1934) (last read ?). Dick and Dorothea in the Norfolk Broads.
Pigeon post (1936) (last read 2011).
This one is unusual in that it's mainly a real-life adventure about gold mining,
which involves almost no sailing and only slight elements of fantasy or make-believe.
Slow-starting, it turns into an exciting story later on.
First appearance of Timothy.
We didn't mean to go to sea (1937) (last read 2005).
A gripping story in which the Swallows are accidentally set adrift in a yacht
at night, in bad weather, and after much adventure eventually wind up in Holland.
Ransome made the same journey himself in real life by way of research.
Secret Water (1939) (last read 2011).
The Swallows and Amazons explore low-lying islands on the Essex coast
and make some new friends.
It's an eccentric and rather unpromising choice of scenario;
Ransome makes an acceptable story out of it,
but I'd rather have had another Lake District story.
The Big Six (1940) (last read ?). Dick and Dorothea in the Norfolk Broads again.
Missee Lee (1941) (last read ?). Another fantasy story like Peter Duck, but this time about Chinese pirates.
The Picts and the Martyrs (1943) (last read 2011).
A well-plotted story with many interesting details,
although the Swallows are absent and the Amazons much hampered by the presence
of Great Aunt Maria, so that Dick and Dorothea become the central characters.
It functions as a direct sequel to Pigeon post, so there's a slight return
to the subject of mining, and Timothy reappears.
Great Northern? (1947) (last read ?). A rather disappointing book about birdwatching in Scotland, although it reunites the full set of children from the Lake District.