The Strait of Hormuz is a narrow waterway that links the Persian Gulf with the Gulf of Oman. At its narrowest point it measures roughly 21 miles (34 kilometers) across. That distance may sound short, but the Earth’s curvature and local topography play a big role in what the eye can capture from sea level.
Visibility across any sea lane depends on three main factors: the height of the observer, the height of the opposite shore, and atmospheric conditions. In clear daylight and with a modest elevation—say a balcony or a hill—most people can indeed glimpse the far side, especially where the coastline rises into cliffs.