We explore a simple model of water : Lennard-Jones disks in two dimensions, subject to a Gaussian orientation-dependent hydrogen-bond function. The model, originally developed by Ben-Naim, shows the anomalous features of water and aspects of the hydrophobic effect. Here we further explore its phase diagram and related properties by NPT Monte Carlo simulations. (C) 1998 Elsevier Science B.V. All rights reserved.