Swallows and Amazons (movie, 2016)

Four children dream of escaping the tedium of a summer holiday with their mother. When finally given permission to camp on their own on an island in the middle of a vast lake, they are overjoyed. But when they get there they discover they may not be alone… The battle for ownership of a lonely island teaches them the skills of survival, the value of friendship and the importance of holding your nerve.