Slumping oil prices are spurring 4,000-mile (6,400-kilometer) diversions of tankers filled with diesel and jet fuel as the price of ship fuel plunges, opening up trading opportunities. At least five tankers will deliver refined products to European ports in August and September, sailing around South Africa rather than using the normal shortcut through Egypt’s Suez Canal, ship tracking data show. The falling cost of fuel oil, used to power ships, has made longer voyages viable at a time when there are advantages for traders to keep cargoes at sea. Long-distance shipments between continents have increased this year, according to Torm A/S, world’s second-biggest publicly traded product-tanker owner.