while on vacation on northern australia and gracie ( diana glenn ) and her husband adam ( andy rodoreda ) and her young sister lee ( maeve dermody ) decide to take the blackwater barry tour in the swamp for fish . their guide jim ( ben oxenbould ) use a small motor boat and take the tourist along the river to a remote spot . when they stop and they be attack by a huge crocodile that capsize their boat and immediately kill jim . the three survivor climb a tree and when they realize that help would never come to rescue them and they decide to try to find a way out of their sheltered location . however and in the muddy water and their boat be flip and the crocodile stalk the trio under the water . black water be a tense and realistic and dramatic low budget movie and in accordance with the warning in the beginning and base on a true event . the acting of the unknown diana glenn and maeve dermody and andy rodoreda be top notch and give credibility to this simple but scary story . there be many similarity between this movie and prey and but in different environment . my vote be seven . title ( brazil ) represent medo profundo ( deep fear ) .