Magic by the lake

"On a vacation with their mother and stepfather, Jane, Mark, Katharine, and Martha find themselves overwhelmed with a lakeful of magical adventures after Mark captures an ancient turtle that seems to have extraordinary powers."@en
"On a vacation, four children find themselves with an entire lake full of magic, which they must tame in order to find the treasure that waits for them."@en
"On a vacation, four children find themselves with an entire lake full of magic, which they must tame and learn how to handle in order to find the treasure that waits for them."@en
"On a vacation, four children find themselves with an entire lake full of magic, which they must tame and learn how to handle in order to find the treasure that waits for them."
"Sequel to: Half magic."@en
"On a vacation with their mother and stepfather, Jane, Mark, Katharine, and Martha find themselves overwhelmed with a lakeful of magical adventures after Mark captures an ancient turtle that seems to have extraordinary powers."