PARIS — As the world was transfixed by the Titanic-like imagery of the partly submerged Costa Concordia and the frantic efforts to save the fuel-laden vessel in rough seas off the Tuscany coast, questions swirled on Monday about the enormous cruise line industry, which operates without much regulation.

The ship’s detained captain, Francesco Schettino, was accused by his bosses of deviating from a fixed, computerized course to show off his beautiful $563 million boat, carrying more than 4,200 passengers and crew members, to the people of Giglio Island on a still Friday night, crashing it on a reef.

But as shares in the ship’s parent company — Carnival Corporation of Miami, the world’s biggest cruise line operator — slid by nearly a fifth and the owners and insurers tried to add up the cost of the disaster, there were more troubling issues raised about how the cruise industry is supervised and controlled.