Watch Atchafalaya Houseboat for Free: How to Stream the Movie Online at 123Movies. . The Atchafalaya is a mysterious land, as much underwater as above. Its lush environment is home to alligators, egrets, black bears – and for a time two people who yearned for a simple, natural life. Atchafalaya Houseboat shares the experiences of Gwen Roland and her companion Calvin Voisin, who left civilization in the turmoil of the early 1970s for the unspoiled beauty of the nation’s largest river swamp, Louisiana’s Atchafalaya Basin.