The island of Perim divides the strait into two channels, of which the eastern, known as the Bab Iskender (Alexander's Strait), is 2 miles (3 km) wide and 16 fathoms (30 m) deep, while the western, or Dact el Mayun, has a width of about 16 miles (25 km) and a depth of 170 fathoms (310 m).