It has been predicted that the seismic propagation velocities of sea ice affect the propagation of sound in ice covered arctic waters. Since very little data are available on propagation velocities, a series ofin situmeasurements of propagation velocities and associated density, temperature, and salinity profiles have been made in sea ice. Seismic energy from predominantly shear or compressional wave sources was propagated over ranges of a few hundred meters to two three‐component geophone arrays. Propagation paths in smooth and in slightly rough annual ice were selected. Plate, flexural, and shear wave arrivals were clearly identified from their polarizations and particle velocities. A reduction in plate and flexural wave velocities was observed in the rough annual ice compared to the smoth annual ice.