The 78-metre (255-foot) riverboat Bulgaria was given a lift off the riverbed earlier Friday but still remains under water, said spokesman for transport ministry Timur Khikmatov.

The crews must over the next hours hermetically seal it and pump out the water before proceeding with the plan to pull it to the surface and haul it to a dock, he said.

“It could take several hours,” Khikmatov told AFP. The boat’s stern is now six metres above the the bottom of the river.

An elaborate operation involving dozens of divers and two huge cranes in the central region of Tatarstan began on Saturday.

The operation has taken much longer than expected as crews have been hit by a number of setbacks, including low-visibility and a snapped steel cord.

Earlier this week the crews managed to steady the boat, which was lying on its right side and getting sucked into the riverbed silt.

The overcrowded 56-year-old boat went down on July 10 in a storm in the country’s worst boat disaster in recent memory, which the Kremlin blamed on safety breaches.

Authorities have so far found the bodies of 114 people, including 28 children, while another 15 are listed as missing.