The captain, chief mate, second mate, third mate, chief cabin steward, and housekeeper of the Greek-flagged vessel were arrested after the accident, a merchant marine ministry spokeswoman said earlier on Saturday.
All were released pending further investigations.
Two French passengers are still missing after the sinking of the Sea Diamond, which hit rocks on Thursday and sank off the coast of the Greek island of Santorini.
The rest of the 1,154 passengers and 391 crew were safely evacuated.
The 469ft vessel hit a well-marked and charted reef in fair weather inside Santorini's sea-filled crater. The ship had been due to dock a few minutes later.
"Whoever is responsible for this will be held accountable in the strictest way"
Fanny Petralia, Greek Tourism Minister
The sinking vessel was evacuated in a three-hour rescue operation, but Jean-Christophe Allain, 45, and his 16-year-old daughter, Maud, from Doue-la-Fontaine in western France were later listed as missing, feared to have been trapped in their flooded lower-deck cabin.
Largest Greek rescue
The ministry spokeswoman said the search for the two continued, while divers continued to investigate the hulk of the Sea Diamond.
Officials were also carrying out a clean-up effort for fuel that leaked out of the 21-year-old vessel, which sank 15 hours after the accident.
|"The vessel had highest level of safety standards and was equipped with the latest navigation systems" |
Giorgos Stathopoulos, Louis Cruise Lines
"The vessel maintained the highest level of safety standards and was equipped with the latest navigation systems," said Giorgos Stathopoulos, spokesman for the ship's operator, Louis Cruise Lines.
Thursday's evacuation was the largest Greek rescue operation since the September 2000 Express Samina ferry disaster, which killed 80 people near the holiday island of Paros when it struck rocks in the night and sank.
It also created a major headache for officials in Greece's key tourism industry - which accounts for an estimated 18 per cent of the country's Gross Domestic Product.
"Whoever is responsible for this will be held accountable in the strictest way," Fanny Petralia, the tourism minister said. "Greece is a major tourism destination and incidents like this must not be allowed to occur. Authorities handled the rescue very well."
Manolis Kefaloyannis, the merchant marine minister, said the evacuation "was orderly and successful.
"Every decision was taken in a way that would not endanger lives".
But some passengers complained of an insufficient supply of life vests, little guidance from crew members and being forced into a steep climb down rope-ladders to safety.
Most of the passengers were American, but there also were groups from Canada and Spain.