In the opening pages of Elisha Cooper’s wondrous “River” (Orchard/Scholastic, ages 4-10), a woman waves farewell to two children and an adult and sets out on a 300-mile journey by canoe. Her route — from quiet mountain lakes to the busy headwaters of the Hudson — is filled with adventure, wonder and excitement. There’s a bear cub who shares the woman’s interest in a blueberry bush, an eagle searching for food and the quiet of being entirely alone. The woman sketches the creatures she encounters — otters, dragonflies, kingfishers. There are plenty of challenges along the way: an encounter with thundering rapids, a tugboat suddenly bearing down on the woman in her small craft, the squall that tips her canoe and loses her tent. In an author’s note, Elisha Cooper estimates that this journey would take about 30 days and “would take considerable planning, stamina, and heart.” Cooper’s fine-lined pen and watercolor illustrations capture the small details of the trip — the canoe and the way it moves through water, the way the shoreline changes, the shapes of bridges and buildings — and sets them in the wide landscape of river and sky. As moose and bears and starry nights give way to towns, storms and big boats, and finally a welcome home, young readers will feel that they, too, have been on a marvelous, bold voyage.