Preheat the oven to 375 degrees F (190 degrees C). Grease a 9x9-inch baking dish.

Whisk baking mix, milk, 1/3 cup sugar, and oil together in a bowl until no large lumps remain. Pour into the prepared baking dish. Whisk water and 2/3 cup sugar in a clean bowl until mixed. Gently fold in berries until evenly coated; spread berry mixture over baking mix batter.

Bake in the preheated oven until golden on top and fruit is bubbling, about 45 minutes.