In this paper, we present an efficient implementation of a state-of-the-art high-resolution explicit scheme for the shallow water equations on graphics processing units. The selected scheme is well-balanced, supports dry states, and is particularly suitable for implementation on graphics processing units. We verify and validate our implementation, and show that use of efficient single precision hardware is sufficiently accurate for real-world simulations. Our framework further supports real-time visualization with both photorealistic and non-photorealistic display of the physical quantities. We present performance results showing that we can accurately simulate the first 4000 s of the Malpasset dam break case in 27 s using over 480,000 cells (dx = dy = 15 m), in which our simulator runs at an average of 530 megacells per second.