This book is a narrative told from the point of view of a young girl who is showing her visiting cousin a coastal salt marsh. The children visit the marsh every day for four days, slowly building their knowledge of the ecosystem. As they make their way through the tall marsh grass, the two children slip and slide on marsh mud, discover clusters of ribbed mussels at the base of the grass, and watch as fiddler crabs skitter from burrow to burrow around the edge of a creek. Representative of intertidal marshes throughout the world, the coastal salt marsh described in this book is typically shared by both land and marine mammals, presenting a unique ecosystem at the water's edge.