Glacier calving can cause violent impulse waves which, upon landfall, can lead to destructive tsunami-like waves. Here we present data acquired during a calving event from Eqip Sermia, an ocean-terminating glacier in West Greenland. During an exceptionally well documented event, the collapse of 9 × 10⁵ m³ ice from a 200 m high ice cliff caused an impulse wave of 50m height, traveling at a speed of 25–30ms−1. This wave was filmed from a tour boat in 800m distance from the calving face, and simultaneously measured with a terrestrial radar interferometer and a tide gauge. Tsunami wave run-up height on the steep opposite shore in 4km distance was 10–15m, destroying infrastructure and eroding old vegetation. These observations indicate that such high tsunami waves are a recent phenomenon in the history of this glacier. Analysis of the data shows that only moderately bigger tsunami waves are to be expected in the future, even under rather extreme scenarios.