Final answer:
The waterway between the Persian Gulf and the Gulf of Oman/Arabian Sea that is extremely dangerous is the Strait of Hormuz.
Step-by-step explanation:
The waterway between the Persian Gulf and the Gulf of Oman/Arabian Sea that is extremely dangerous is the Strait of Hormuz. It is a narrow passageway that provides the only sea passage from the Persian Gulf to the open ocean and is one of the world's most strategically important choke points. Oil tankers traveling through the strait have leaked oil, affecting the environment and endangering biodiversity.