Also have a look at the ASTER GDEM data for elevation and water body classification: https://asterweb.jpl.nasa.gov/gdem.asp. I have managed to successfully use this in one of my own projects, but it did take some processing to get it into a different data format for my purposes. Although this data has only about a 30-metre resolution, all the raw data does seem to be available for the vast majority of the globe (between 83 south and 83 north latitude).