What do Sandhogs do? Most people have no idea what a Sandhog is. Sandhogs are the hard working men and women who dig the tunnels below New York City that make the City work. The Sandhogs are part of the international union of North America. They are currently working on NYC water tunnel #3 and have worked on the Lincoln, Holland, Queens-Midtown, and the Brooklyn-battery tunnels along with most of New York City's subways, waterways and sewers.