Complex sentence: When the ship canal opened in January 1894 it was the largest river navigation canal in the world, and enabled the newly created Port of Manchester to become Britain's third busiest port despite the city being about 40 miles (64 km) inland.
Split into simpler sentences: When the ship canal opened in January 1894 it was the largest river navigation canal in the world. It enabled the newly created Port of Manchester to become Britain's third busiest port--despite the city being about 40 miles (64 km) inland.