Yal Tengri, also known as the Great Ice Sea, was an arm of the ocean that covered the north pole of Toril. All sorts of cold-loving creatures were found in its waters. The sea was open for about six months of the year. Fall brought rapidly dropping temperatures and the water gradually froze over. In the winter Yal Tengri was basically a sheet of ice, broken only by a few dangerous shifting ribbons of open water. As spring dawned, icebergs calve off the permanent ice cap and the melting began.