War is an environmental disaster, at whatever scale. One of the emerging dangers of the U.S.-Israel war on Iran is the oil spilled from tankers that have been attacked. But there is also a risk of collision and cargo leakage between ships that have turned off their transponders in order to evade detection by either hostile side.

The New York Times reports that maritime experts say the threats of a catastrophic oil spill in ecologically sensitive waters around the Strait of Hormuz are increasing, as the conflict has widened and more tankers are going “dark.”

According to maritime data firm Kpler, since March 1, there have been 1,514 dark crossings in and out of the Persian Gulf, and three different oil slicks are spreading through the area, according to maritime security experts who are tracking the spills.

One spill, believed to have been caused when a projectile hit a cargo vessel in the Strait of Hormuz on August 3, has sent oil washing up on the coast of Iran’s Qeshm Island and its sensitive mangrove ecosystems. A second slick has been reported near the island of Sirri, an oil and gas hub in the gulf. The Times says the origin of that spill has not been verified.

But perhaps the worst spill so far is from the tanker Caroline Bezengi, which was carrying nearly one million barrels of Russian crude bound for Asia, making it subject to international sanctions against the purchase of Russian oil. It ran aground off the coast of Oman after an unexplained explosion in early June. The resulting oil slick now covers an estimated 400 to 500 square miles, and is threatening a nature reserve and coral reefs, as well as washing up on the beaches of the mainland in an area known as the Turtle Coast.

Restitution by shipowners is unlikely. According to Kpler, the vast majority of the estimated 300 ships that have been responsible for the 1,514 dark crossings since March 1 carry no insurance.