Iran has deployed submarines directly in the Strait of Hormuz.

This area is a mandatory passage for the world’s oil tankers, with one-third of the crude oil passing through here.
Previously, Iran could disrupt shipping lanes with naval mines, speedboats, and missiles; now that submarines have been brought in, the situation has been directly escalated.
Next, as long as there is a little friction, oil prices will have to rise further, and market risks will also be amplified along with it.

1: Globally, 31%-34% of seaborne crude oil (about 13.4 million barrels per day) goes through here; combined with refined oil products, the total is about 18.5 million barrels per day.
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2: For Middle Eastern crude oil imports to China, India, and Japan/Korea, 45%-67% rely on this route.
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3: At the narrowest point, it is only 33 kilometers wide, with an average water depth of less than 70 meters—making it hard for large fleets to operate; small submarines plus naval mines are a natural strong suit.