The cost of hiring an oil tanker on the industry’s benchmark trade route topped $1 million a day for the first time, as the Iran war leaves too few ships willing to cross the Strait of Hormuz to collect cargoes. Vessels hauling oil from inside the Persian Gulf to China were being hired at $1.035 million a day, according to data from the Baltic Exchange in London on Monday.

The benchmark route has become less relevant during the war because the main means of exporting Persian Gulf oil has shifted to shuttling barrels through Hormuz for collection just outside by tankers that don’t want to navigate the strait. Even so, transporting crude to China from the Gulf of Oman, which doesn’t require transit through the chokepoint, costs the equivalent of about $644,000 a day. In bad markets in the past, the same ships sometimes barely covered their running costs.

Shipping costs have been propelled higher by a combination of factors, many of which center around the Iran war and a giant bet by a secretive Korean tycoon. The supersized earnings also partly reflect oil-refining margins that have spiraled out of control because wars in Iran and Ukraine mean world isn’t making enough fuel to meet demand. That’s spurring refiners to keep purchasing and shipping whatever barrels they can get because it’s still profitable for them to process the oil into finished fuels like diesel and gasoline.

At the same time, the number of vessels shuttling cargoes out of the Hormuz is adding time to each tanker journey, sucking up vessel supply. That comes alongside disruptions to Saudi oil flows from Yemen’s Houthi rebels, which has forced some ships to sail a voyage that’s 30 days longer around Africa.