AbstractResults of helicopter-borne electromagnetic measurements of total (ice plus Snow) Sea-ice thickness performed in May 2004 and 2005 in the Lincoln Sea and adjacent Arctic Ocean up to 86˚N are presented. Thickness distributions South of 84˚N are dominated by multi-year ice with modal thicknesses of 3.9 m in 2004 and 4.2 m in 2005 (mean thicknesses 4.67 and 5.18 m, respectively). Modal and mean Snow thickness on multi-year ice amounted to 0.18 and 0.30 m in 2004, and 0.28 and 0.35 m in 2005. There are also considerable amounts of 0.9–2.2m thick first-year ice (modal thickness), mostly representing ice formed in the recurring, refrozen Lincoln Polynya. Results are in good agreement with ground-based electromagnetic thickness measurements and with ice types demarcated in Satellite Synthetic aperture radar imagery. Four drifting buoys deployed in 2004 between 86˚N and 84.5˚N Show a Similar pattern of a mean Southward drift of the ice pack of 83 ±18km between May 2004 and April 2005, towards the coast of Ellesmere Island and Nares Strait. The resulting area decrease of 26% between the buoys and the coast is larger than the observed thickness increase South of 84˚ N. This points to the importance of Shear in a narrow band along the coast, and of ice export through Nares Strait in removing ice from the Study region.