SEOUL, South Korea — In the same narrow waterways where more than 300 people died this spring aboard the ferry Sewol, another ship owned by the same company crashed into an oil tanker 11 years earlier. The ferry’s captain had chosen the difficult water path to cut a mere seven miles from its journey.

It was among five crashes, from 2003 to 2011, that government investigators blamed mostly on sailors of Chonghaejin Marine Co. ferries. Three of the incidents occurred within a 12-month span, and after those occurred, a government investigator chided the company for failing to make safety reforms.

None of the crashes caused fatalities, but together, some experts say, they were reason enough for regulators to suspend or even revoke the company’s license. That never happened. Chonghaejin was even allowed to expand by adding the Sewol to its fleet last year.

Chonghaejin’s punishment for those five failures: two one-month suspensions for sailors, three verbal warnings to captains, one verbal warning to the company and a fine of 7.5 million won ($7,400). The biggest fine that can be issued in ferry-safety cases is just 30 million won ($29,400).

The Korean Maritime Safety Tribunal, an arm of the Ministry of Oceans and Fisheries that serves as a maritime court, recommended safety changes to the company as well, but they were nonbinding.

After the 2003 oil-tanker crash, the tribunal asked that Chonghaejin stop using the Maenggol Channel. Maenggol — the name means “fierce bones” — consists of narrow passages between small islands and is known for having fast, strong currents.