What is the Orthodox doctrine of hell? I honestly do not know. I do know what many Orthodox have taught about hell during the past hundred years or so, and I know something about what the Church Fathers taught about it during the first millennium of the Church’s history; but I cannot tell you what the Orthodox Church authoritatively and irreformably teaches about hell, beyond the fact that it is a horrifying possibility and therefore a destiny best avoided. As the Orthodox Church sings at the Saturday Vespers of the Sunday of the Last Judgment:

When the thrones are set in place and the books are opened, then God will take His place on the judgment-seat.
What a fearful sight! 
As the angels stand in awe and the river of fire flows by:
What shall we do, who are already condemned by our many sins, as we hear Christ call the righteous…