Costa Concordia Cruise Ship Tragedy: Cave Divers Race To Find Survivors (PHOTOS)

Divers are hurrying as quickly as possible to rescue any possible remaining survivors from the Coasta Concordia cruise ship that ran aground off the coast of Tuscany, Italy on Saturday and keeled over.

On Monday, the head of the Italian Coast Guard said there were at least 29 people still unaccounted for -- a sharp increase from previous estimates -- according to CNN. Among the missing are two Americans.

Three survivors were pulled from the vessel on Sunday, and cave divers are continuing to search for anyone still inside.

But according to Reuters the mission isn't simple by any means. Due to a massive amount of debris, the ship is a maze of dead ends and winding hallways.

Speleologists, as they are known, are used to diving in dark and enclosed spaces. The ship's hallways, cabins and dining rooms are similar to caves -- but caves do not have floating furniture or doors that may be jammed shut.

Some have drawn comparisons to the infamous Titanic disaster and this crash off the coast of Italy, as many of the survivors described their ordeal, having to crawl through long almost vertical hallways and stairwells, the AP writes. Whether that comparison is fair remains a subject of debate.

Scroll through the slideshow below to see submerged portions of the ship, including a large breach in the hull.