The Suez Canal temporarily suspended traffic on Thursday as efforts to dislodge a 400 m (430 yard) long container vessel that has blocked the waterway continued for a third day, with eight tugs working to straighten the ship.
The Ever Given vessel, almost as long as the Empire State Building is high, ran aground diagonally across the single-lane stretch of the southern canal on Tuesday morning after losing the ability to steer amid high winds and a dust storm.
It is now blocking transit in both directions through one of the world's busiest shipping channels for goods, oil, grain and other products linking Asia and Europe.
Eight tugs, the largest of them with a towing power of 160 tons, have been trying to push and pull the Ever Given free of the canal's banks, the Suez Canal Authority (SCA) said in a statement.
Thirteen vessels that sailed south from Port Said in a convoy on Wednesday had dropped anchor in the Bitter Lakes waiting area until navigation could be resumed, it said.
Peter Berdowski, CEO of Dutch company Boskalis, which is trying to free the ship, said it was too early to say how long the job might take.
"We can't exclude it might take weeks, depending on the situation," Berdowski told the Dutch television programme "Nieuwsuur".
He said the ship's bow and stern had been lifted up against either side of the canal.
"It is like an enormous beached whale. It's an enormous weight on the sand. We might have to work with a combination of reducing the weight by removing containers, oil and water from the ship, tug boats and dredging of sand."
Several dozen vessels, including other large container ships, tankers carrying oil and gas, and bulk vessels hauling grain have backed up at either end of the canal to create one of the worst shipping jams seen for years.
Bernhard Schulte Shipmanagement (BSM), the technical manager of Ever Given, said dredgers were working to clear sand and mud from around the blocked vessel while tugboats in conjunction with Ever Given's winches work to shift it.
Marine services firm GAC issued a note to clients overnight saying efforts to free the vessel using tug boats continued, but that wind conditions and the sheer size of the vessel "were hindering the operation".
Japanese shipowner Shoei Kisen apologised for the incident and said work on freeing the ship, which was heading to Europe from China, "has been extremely difficult" and it was not clear when the vessel would float again.
The ship's GPS signal shows only minor changes to its position over the past 24 hours.
Roughly 30% of the world's shipping container volume transits through the 193 km (120 miles) Suez Canal daily, and about 12% of total global trade of all goods.
Shipping experts say that if the blockage is unlikely to be cleared within the next 24-48 hours, some shipping firms may be forced to re-route vessels around the southern tip of Africa, which would add roughly a week to the journey.
Consultancy Wood Mackenzie said the biggest impact was on container shipping, but there were also a total of 16 laden crude and product oil tankers due to sail through the canal and now delayed by the incident.
The load of the tankers amounted to 870,000 tonnes of crude and 670,000 tonnes of clean oil products such as gasoline, naphtha and diesel, it said.
