Coincident, continuous ice force and thickness measurements are presented which have been performed in 2002 on a lighthouse located in drifting sea ice in the Bay of Bothnia near Luleå, Sweden. Level and ridged ice thickness has been profiled both by means of upward-looking sonars (ULS) and electromagnetic induction (EM) sounding. Preliminary results indicate some correlation between forces and overall ice thicknesses, although no careful analysis considering varying ridge properties and different failure modes has been carried out yet. Both, EM and ULS data were well capable of yielding the required ice thickness data, although they have to be interpreted differently. However, EM measurements underestimated the maximum depth of ridge keels by as much as 50%. This might be due to disadvantageous sea water properties in the Bay of Bothnia.