Swallowdale is the second novel in Arthur Ransome's popular and much-loved Swallows and Amazons series. The story takes place a year after Swallows and Amazons, and follows the continuing exploits of the Walker and Blackett families on 'the Lake', a place which is a mixture of Coniston and Windermere in the British Lake District.

A promising summer holiday is nearly ruined by the unfortunate arrival of Nancy and Peggy Blackett's dreaded Great Aunt Maria (pronounced Mariah, no doubt). Captain John then further upsets matters by damaging Swallow. With both boats in dock, the Walkers take to camping on the western shore of the Lake, on the edge of the moor, in a little valley they name Swallowdale. Several lively adventures ensue as the Blackett sisters try to have a holiday in spite of the presence of their domineering aunt. These include another encounter with the charcoal-burners whom the children met in the same area the previous year, and the daring ascent of Kanchenjunga - alias Coniston Old Man.

Also notable are a number of references to the childhood of Mrs Blackett and her brother Jim 'Captain Flint' Turner, and allusions to the Peter Duck mythology created by the children. Horrible Great Aunt Maria returns in The Picts and the Martyrs, and the story of Peter Duck is told in the novel of the same name.