The high-risk, high-reward business of moving oil through the Strait of Hormuz has grown riskier—and more rewarding.

Despite repeated attacks from Iran, oil tankers and other commercial vessels have kept moving through the narrow waterway, which links Persian Gulf producers to the open ocean and serves as the primary export artery for the region's oil. With protection from the U.S. military and added capacity from pipelines that bypass the strait, Persian Gulf oil flows have returned to prewar levels.

Seeking to reassert its leverage over the global oil chokepoint, however, Iran has recently intensified drone and missile strikes on ships, including vessels outside the immediate vicinity of Hormuz. Traffic has dipped in response, but ships continue to cross. Many now make shuttle runs in and out of the Gulf, unloading oil cargoes through ship-to-ship transfers before other vessels deliver the barrels to customers.

For crews willing to tolerate the risks, the payoff is substantial. Tanker captains can earn $100,000 a month for transiting the strait, plus a $50,000 bonus for each trip, sources told the Financial Times. That danger money marks a steep increase from regular pay of about $15,000 a month, and it has become necessary for shipowners to keep their fleets crewed. Sailors, who typically make as little as $1,500 a month, can lift their earnings to at least four to six times their normal rates on Hormuz trips, according to the report.

Other hot spots also carry hazard enhancements, though at lower rates. According to the FT, captains and sailors receive double pay in the southern Red Sea, where Houthis have been attacking Saudi ships, and in the Gulf of Oman, where many ship-to-ship transfers take place after Hormuz shuttle runs.

Because many vessels and their crews are dedicated to the shuttle runs, they operate in near-constant peril—allowing them to stack up bonuses and danger money on every voyage. One source told the FT that sailors brave enough to stomach the persistent threat of attacks are "almost being viewed as mercenaries," though some unwilling crew members are reportedly being pressured to remain onboard.

The human toll has been severe. Since the Iran war began on Feb. 28, at least 93 ships have been hit and 24 sailors have been killed, according to the International Maritime Organization, the United Nations agency that oversees global shipping.

The costs extend well beyond hazard pay. Shipowners are also paying for insurance, and war risk coverage can command 6% to 10% of a vessel's value—translating to as much as $20 million for a supertanker sailing through the Gulf.

Those expenses have made shipping extraordinarily expensive. Freight rates for cargoes crossing the Strait of Hormuz hit a record high of $1.3 million per day, up from daily rates of $20,000 to $50,000 last year. The sheer number of ships required to move oil out of the Gulf has also contributed to a global tanker shortage, driving up freight rates around the world.

Shipbroker Gibson pointed out that hiring a tanker to travel from the U.S. to China now costs about $80 million—more than the $74 million price tag for a standard SpaceX Falcon 9 launch, a comparison highlighted in a post on X. Brokerage SSY estimated that rates are now the highest since the advent of the supertanker in the 1960s, even after adjusting for inflation.

Shipping costs have grown so extreme that oil producers and even commodities traders are looking to own tankers outright to control expenses. But if freight costs climb too high, they could erase the margins earned on oil and refined fuels. European refiner Repsol, for example, saw its margin fall from $36 per barrel in the third quarter to $15 in October, according to analysts at RBC. Further margin compression could eventually force refiners to process less crude.

The hazard premium in the Persian Gulf could still worsen. Analysts have warned that Iran's regime, facing an existential threat to its rule, could re-escalate the war and attempt to take back its grip on the oil trade. Esfandyar Batmanghelidj, founder and CEO of the Bourse & Bazaar Foundation think tank, recently noted that Iran retains the ability to destroy regional oil infrastructure—such as drilling and refining capacity—and could escalate if President Donald Trump rejects diplomatic off-ramps.

"Iran did not wage a scorched earth campaign—but it may yet do so if the current situation persists for too long," he wrote in a post on X late last month. "That is what everyone who actually follows this region and its dynamics is worried about." The pressure points to watch from here: whether Gulf flows hold at prewar levels, whether war risk premiums and freight rates climb further, and whether diplomatic off-ramps ultimately taken.

This story was originally featured on Fortune.com.