The size distribution of sea ice floes was observed by coordinated Landsat imagery and video monitoring conducted from an icebreaker and a helicopter for an area 38 km ¿ 26 km in seasonal sea ice in the southern Sea of Okhotsk in February 2003. The combination of imagery on several scales allowed measurements of ice floes over three orders of magnitude, from 1 m to 1.5 km. Two different regimes were observed: floes larger than about 40 m have a power-law number density with an exponent of -1.87, in the lower range of earlier results. Below 40 m, the power law exponent is -1.15. The cause of these two different regimes is hypothesized to lie in the effects of swell on floes of different sizes and thicknesses. The importance of the floe size distribution for lateral melting is elucidated.