Dragons in the Waters (ISBN 0-374-31868-9) is a 1976 young adult murder mystery by Madeleine L'Engle, the second title to feature her character Poly O'Keefe.

She has also just read Quentin Phair's letters and journals, thus learning belatedly that Simon's heroic ancestor left behind a wife and son among the Quiztano Indians of Dragonlake in Venezuela.

The connection between Quentin Phair and Umara of the Quiztanos is the underlying cause of Simon's current predicament, part of a tangled web of murder, smuggling, blackmail and a generations-old grudge.

Alejandro Hurtado, a friend of Tallis, initially arrests Jan, a Dutch sailor with Quiztano blood, but the ship's first mate, Lyolf Boon, soon confesses to Phair's murder.

After some initial resistance, Simon decides to stay at Dragonlake and continue the good work that his ancestor started with the Caring Places.

At the time of the book's publication, Kirkus Reviews said, "Of all L'Engle's novels, we find this the most satisfying, perhaps because it doesn't demand to be taken with such deadly seriousness.