We report flow speed variations near the front of a tidewater glacier in Greenland. Ice flow near the glacier front is crucial for the mass loss of the Greenland ice sheet, but in situ data are hard to obtain. Our unique in situ GPS data revealed fine details of short-term speed variations associated with melting, ocean tides, and rain. The results are important for understanding the response of tidewater glaciers to changing environments, such as warming, more frequent rain, and ice thinning.