Hydro3D is a finite difference Navier Stokes solver that permits accurate and efficient Large Eddy Simulation (LES) of turbulent flows. It has been developed by Prof. Thorsten Stoesser and co-workers at Cardiff University, UK, primarily for use in the simulation of environmental fluid dynamics. If you are interested in using and/or developing the code, or if you would like to discuss opportunities for collaboration, please send a mail to ourobarbap@cardiff.ac.uk.