Here's What You Need to Remember: Despite the difficulties in anti-submarine operations in both the Persian Gulf and the Strait of Hormuz, the Iranian submarine movement would be severely limited by the shallow depth, especially in the Gulf. Outside the Gulf, though, is another matter.
Iran maintains a large fleet of submarines as the strategic port of Bandar Abbas, the majority of which are domestically manufactured. Most of Iran’s underwater fleet are midget submarines, designed for infiltration and sabotage, or small displacement submarines that may have limited endurance and dive depth. However, the Soviet Kilo-class is their best against the U.S. Navy if a conflict were to ever occur.