This paper introduces an experimental rig used to produce data for the validation of computational models of natural convection within water in an enclosed cavity. The rig consisted of a rectangular cavity with the two long sides maintained at constant temperature. All other surfaces were insulated and adiabatic except for the top surface which was a free surface with an air gap between the free surface and the insulation. Experimental data in the form of velocity, ice growth rate and profiles are presented at 30 min time steps with a cold wall temperature of -10 degrees C and hot wall temperature of 5 degrees C. The data produced has systematic and random errors of 0.4% and 0.5%, respectively. (c) 2006 Elsevier Ltd. All rights reserved.