Have you ever thought about how marine tanker and aircraft operators take care of their fuel needs? Yeah, me neither. At least not until I came across World Fuel Services (NYSE:INT) and dug a little deeper.

World Fuel offers fuel services and logistics to customers in the marine and aviation markets. The marine business consists mostly of tankers, container ships, and dry bulk cargo carriers, while the aviation business serves passenger, cargo, and charter airlines.

While the marine transport market remains robust and World Fuel expands its aviation business, its results for the second quarter were solid. Total revenue climbed more than 53% to more than $2 billion with a near 50/50 split between marine and aviation. While a nearly 73% increase in price per ton of fuel sold boosted the marine business, volumes declined as the company looked to minimize high-volume/low-profit transaction business. On the aviation side, the average price per gallon of fuel climbed almost 48%, and volumes grew as well.

This business has razor-thin margins, and this quarter was no exception. Overall operating margin was down slightly to 0.57% from 0.65% a year ago. While marine margins improved slightly, higher operating expenses hurt the aviation side. At the bottom line, World Fuel posted 50% net income growth overall for the quarter.

In some sense, World Fuel is benefiting from the fact that fuel is not something that most people want to think about much. Fuel is a major expense for ship and aircraft operators, and there are clear benefits to minimizing this expense wherever possible. That said, these transport operators are specialists in transport, not fuel.

So enter World Fuel.

World Fuel has an international footprint keenly focused on fuel logistics -- that's what it does, and that's all it does. With its expertise, it can offer much more efficient fuel supply management. Consequently, it can save its clients money while also producing a nice profit for itself. Saving money on fuel is something that could benefit every airline -- whether it's Southwest (NYSE:LUV), Continental (NYSE:CAL), or JetBlue (NASDAQ:JBLU) -- not to mention every shipping company.

Although the stock has had a respectable run, its valuation isn't bad. Looking just at the price-to-earnings ratio ignores this company's free cash flow leverage, and the stock trades at a trailing enterprise value-to-free cash flow of only about 11. Apart from valuation, though, this is a company with a 19% return on equity, a solid value proposition for customers, and an opportunity to grow at sea, in the air, and on land as well.

There aren't many companies like World Fuel, so here are Takes on the industries it serves:

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).