anchor: The winding channel is 30 km (18 miles) long and about 2 km (11.2 miles) wide, narrowing to 750 metres (2,250 feet) at Rumeli Hisare.
positive: The channel is 30km long, 2km wide, and narrows at Rumeli Hisare.
negative: The channel is 100km long, 5km wide with its narrowest point at 2km.