The 1999 Kocaeli earthquake resulted in large-scale damage to structures and a death toll of more than 20,000. Numerous liquefaction and associated ground deformations caused by the earthquake were particularly observed along the southern coasts of Izmit Bay and Sapanca Lake, as well as the city of Adapazari. The paper discusses the soil liquefaction and lateral spreading along the southern coast of Izmit Bay. A microzonation map was created using the data from liquefaction susceptibility analyses and a liquefaction severity index. The predicted liquefiable zones showed good agreement with site observations. The assessment suggests that the amount of liquefaction-susceptible layers in the soil profile reduces away from the coastal zone.