During the 5 August to 30 September 2005 Healy Oden Trans-Arctic Expedition a trans-Arctic survey of the physical properties of the polar ice pack was conducted. The observational program consisted of four broad classes of snow and ice characterization activities: observations made while the ship was in transit, ice station measurements, helicopter survey flights, and the deployment of autonomous ice mass balance buoys. Ice conditions, including ice thicknesses, classes, and concentrations of primary, secondary, and tertiary categories were reported at 2-hour intervals. Pond fractions were large early in the cruise at the southern edge of the ice pack, reaching peak values of 0.5 and averaging 0.25. Ice concentrations ranged from 0.8 to 1.0 north of 79°N, save for an area between 88°30′N and 89°30′N, where polynyas and thin ice were observed. Surveys of snow depth, ice thickness, and ice properties were conducted at ice stations. Thickness observations suggest a general latitudinal trend of increasing ice thickness moving northward, with considerable variability from floe to floe and within a single floe. Average floe thicknesses varied from 1.0 to >2.8 m, and the standard deviation of thickness on an individual floe was as large as 1 m. Ice crystallography showed a large amount of granular ice. The average optical-equivalent soot content was 4 ng C g−1 for new snow, 8 ng C g−1 for the surface granular layer of multiyear ice, and 18 ng C g−1 for the interior of multiyear ice, indicating a tendency of the particulates to concentrate at the surface with melting.