One Guy is betting: zero change, or near-zero change, in sea level since that time (taking into account the possible influence of any local volcanic lava domes!).
Hasnt changed much. The battle of Thermopolye is 1.1 km from the high tide mark today. Oceans lower. Oceans rise. ...hell, Julius Caesar said the best red grapes/wine were in Britain and Normandy! (now red grapes are S. France, N Italy grown).