Sonar devices for detecting underwater objects are provided whereby a set of angled ultrasound transducers are employed to sense ultrasound signals from a plurality of different spatial regions. The angled ultrasound transducers may include a first pair of side-viewing ultrasound transducers and a second pair of ultrasound transducers configured for interrogating forward and reverse directions. The ultrasound signals from the set of angled ultrasound transducers may be processed to identify the presence of underwater objects in each spatial region, and the resulting identified underwater objects may be displayed, on a per-region basis, on a user interface. The ultrasound signals may additionally or alternatively be processed to generate a topographical model of the bed surface, and to generate a topographical surface image based on the three-dimensional topographical model. The topographical surface image may be displayed as a fly-over animation.