Had the crew of an ancient Greek trireme crossed paths with a member of Aegean Marine's (NYSE:ANW) fleet, there's no telling how they might have reacted.

As far-ranging as their hollow ships may have been, the mariners of Homer's day would have soiled their tunics had they known the extent of wine-dark sea now covered by this fuel transporter. Aegean provides fuel to oil tankers, container ships, drybulk carriers, cruise ships, ferries, and other shipping vessels both at sea and in port, and it operates all over the world. Last Thursday, it reported quarterly diluted earnings per share of $0.22 on $951 million in total revenues -- higher than last year's fiscal third quarter by 22% and 167%, respectively.

Helped by sales from its new markets in North America, the U.K., West Africa, and Northern Europe, the company was able to sell 1.3 million metric tons of marine fuel compared to 900,000 over the same three months last year. Moreover, for every metric ton it sold, it kept $32.80 in gross profit. That measure was $24.80 only 12 months ago, so it increased by 32%. Known as the gross spread per metric ton of marine fuel sold, it gauges the average markup Aegean receives for every ton of fuel it sells.

That means its customers paid a heck of a premium for Aegean's fuel -- for comparison, its competitor World Fuel Services (NYSE:INT) kept less than $5 in gross profit per metric ton of marine fuel sold, based on its marine segment gross profit of $114 million and 27.7 million metric tons sold last year. Chemoil's gross take was under $8 per metric ton sold in 2007. A reasonable question investors may want to ask is whether or not Aegean can sustain this markup.

Aside from other resellers like World Fuel Services and Chemoil, Aegean also faces competition from the marine divisions of major oil producers like BP (NYSE:BP), ExxonMobil (NYSE:XOM), and Royal Dutch Shell (NYSE:RDS-A) (NYSE:RDS-B), which market fuel directly to large shipping companies. Furthermore, what's bad for global trade is bad for Aegean, and in addition to worsening macroeconomic conditions, the marine fuel industry is also subject to the physical climate and Poseidon's mood swings. And that’s before we add in Aegean’s $200 million or so in net debt.

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Still, its share price took a flogging in October, and its price-to-earnings growth (PEG) ratio is currently an enticing 0.25. Having spent a good deal adding to its stable of ships, Aegean seems well-suited for further expansion.

If you're brave like Achilles and unafraid of its risks, you might consider how an investment in Aegean's stock would fit into your already well-diversified portfolio.

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Fool contributor Chris Jones does not own shares in any of the companies mentioned. The Motley Fool's disclosure policy never finds itself caught between a rock and a hard place.