13 stunning photos of supertankers and storage tanks reveal the global oil glut in epic proportions

When the price of oil falls, so does the price of the gasoline you buy at the pump. On Monday, the national average was down to just $1.77 a gallon, according to AAA.

At face value, that's good news for gas-station owners, who set their own prices — because they could enjoy wider profit margins.

"Gas stations right now, they have never seen the economics better, ever," Patrick De Haan, an analyst at GasBuddy who's been tracking the prices closely, said. "If this environment could stay consistent, you'd be seeing hundreds of gas stations open up."

But don't be mistaken, Kloza said: This is not a good thing.

Road fuel consumption is down one-third this month, according to Rystad. Plus, gas isn't where stations make their money. They make more in sales of jerky, chips, and other in-store purchases that depend on foot traffic, which has all but evaporated.

Read more: A top energy analyst pinpoints the 3 winners and 3 losers in this week's historic oil-price collapse

They can figure out how much oil the tankers are carrying, in part, by looking at what's called draft — the distance between the waterline and the bottom of the ship.

Companies that track storage like Orbital Insight and Kpler run satellite imagery through computers, which measure the shadows cast across oil tanks. The size of the shadows reveals how much oil is in each of them, as Business Insider previously reported.

Companies also bounce beams of cloud-penetrating radar off the tank tops.

That's what's driving the price of oil into the ground. The value of the international benchmark, Brent crude, is down about 70% since the start of the year. And last week, US crude went negative for the first time in history.

Read more: The price of US crude oil just went negative for the first time. Here's what that really means and why it's not free to fill up your car.

Oil tanks in Cushing, Oklahoma, a major hub, have less than 20 million barrels of spare capacity left, according to Kpler.

"With current rates of build it will be full within a matter of weeks," the firm said in a recent report.

The tanks are named after lids that float on top of the oil to prevent emissions and the buildup of explosive gases. The tops rise and fall with the oil inside.

There are roughly 4.3 billion barrels of crude oil storage worldwide, per Rystad Energy, and roughly two-thirds of that is in floating-roof tanks.

The US is considering banning imports of crude oil, Reuters reports, which could cause the kingdom to re-route the ships.

The 20 or so tankers, which are set to arrive in May, are carrying more than 40 million barrels of crude oil, the Washington Post reports.

Saudi Arabia is one of the top oil-producing nations. And while it agreed to pare back production by more than 20% as part of a record-breaking OPEC deal, it's still producing close to 10 million barrels per day.

Read more: Why the price of oil is continuing to free-fall after a historic supply cut — and when experts think it may finally reach rock bottom

The US Coast Guard, which is typically not patrolling oil tankers, recorded a video of the ships last week.

"Due to the unique nature of this situation, the Coast Guard is constantly evaluating and adapting our procedures to ensure the safety of the vessels at anchor and the protection of the surrounding environment," Commander Marshall Newberry, who works with the Los Angeles Coast Guard, said in a statement.

Oil tankers are typically used to transport — not store — oil. But with global demand down nearly 30% this month and tanks nearing capacity, there's nowhere for the oil to go.

The tankers were carrying more than 20 million barrels of crude oil, making it the largest quantity of crude ever to float off the West Coast, according to Kpler, a company that tracks oil storage.