We report on cavity-dumping of a semiconductor disk laser as a method to generate energetic wavelength-tunable nanosecond pulses with repetition rates ranging from 0.1 to 4 MHz. Experimentally, emission of 24 ns pulses with peak output power of 41 W in a single beam output (and of 30 ns with peak power of 57 W in a combined beam output) with wavelength tuning from 1045 to 1080 nm was obtained. Numerical modeling is also introduced to provide more insight into the most important parameters controlling this mode of operation and to define optimization avenues.