A spatial section of draft across 348 km of sea ice was obtained by moored subsea sonars in the Beaufort Sea in the winter of 1990. The ice field was a mixture of first-year and multiyear types with mean draft of the order of 3 m. Level ice of 0- to 4-m draft occupied approximately 50% of the section: within this fraction, draft values of 0 and 1.5 m were most common, while at 2- to 3-m draft, a noticeable contribution was made by rafted first-year ice. Deformed ice was observed to a maximum draft of nearly 27 m. Keels within the section were identified using both the Rayleigh criterion and a new criterion based on level ice. Both criteria defined exponentially distributed populations but with different e-folding scales. The observations revealed an ice cover whose statistical properties are consistent with other data from the periphery of the polar pack in the Beaufort Sea, but which are much more severe than those of ice found in the seasonal ice zone only a few tens of kilometres to the south. The cross-sectional shape of individual keels was highly variable, but on average the distribution of ice within a keel was an exponential function of draft. The topography of both first-year and old ice subsections of the data was fractal in character, with a dimension of about 1.5 for both ice types. The average mass of sea ice per unit area was estimated as 2540--2970 kg m-2, with 68--73% of this mass contributed by deformed ice. The large uncertainties in these estimates arise because the porosity of keels and the burden of snow or melt water upon the ice are not known. ¿ American Geophysical Union 1995