Heart-breaking footage recorded by a South Korean student inside a capsized ferry that sunk killing him and hundreds of others has emerged.

The video shot by Park Su-hyeon, 17, on his mobile phone, shows students aboard the Sewol, who, clearly unaware of the severity of their situation, take selfies and joke about the looming disaster to exorcise their fears, wondering if they'll make the news.

"Am I really going to die?" a student says two minutes into the video. It was at 8:53am, 16 April; two minutes later a crew member on the bridge made the ferry's first distress call.

"It's like we're becoming the Titanic," a student says as the ship is listing.

The Sewol sank off South Korea southern coast as it was on a journey from Incheon, in the northwest of the country, to the tourist island of Jeju.

325 of the 476 people on board were students on a school trip to the island. Only 174 people survived.