Syria is not Iran’s route to the sea.
Syria has a 193 km (120 mi) coastline on the Mediterranean (a little shorter than New Jersey’s coast).
Iran has a 2,440 km (1,520 mi) coastline on the Persian Gulf and the Gulf of Oman (a little longer than Florida’s coast) and a 740 km (460 mi) on the Caspian Sea (a little shorter than North and South Carolina’s coast).
Even if Iran did not have its own coastline that is 16 times longer than Syria’s, it doesn’t share a land border with Syria, and would have to go through Iraq or Turkey to get there. And if it needs access to the Mediterranean, the Suez Canal has been available since 1869.
Geography was my best subject in fourth grade.