The Italian cruise ship left adrift with more than 1,000 people on board after a power failure now faces a longer journey before reaching land.
The Costa Allegra is being towed to the main island in the Seychelles, rather than a nearer island, and is not now due to arrive until Thursday.
A fire in the ship's generator room on Monday caused it to lose all power.
The ship is from the same fleet as the Costa Concordia, which capsized off the Italian coast in January, killing 32.
A statement from the ship's owners Costa Cruises said that after checking with maritime experts, it had decided that the planned disembarkation on the smaller-but-nearer Desroches Island could not go ahead.
It said the facilities on the island were inadequate to cope with the arrival of so many people.
The statement also said it was not safe enough for the ship to dock in the small port and for guests to get ashore.
The ship will now be towed around 250km (155 miles) further to the island of Mahe, which is home to the capital and largest city, Victoria.
Two tugs approaching the ship are expected to help it arrive there on Thursday.
The company said helicopters would ensure the continuous supply of food and "comfort items" including torches.
The vessel has no air-conditioning or cooking facilities and an emergency generator powering the radio "could fail at any minute", the Italian coast guard says.
Earlier, Costa Cruises stressed that the Allegra - which had been drifting about 32km (20 miles) from Alphonse Island - was steady and conditions were safe. No-one has been injured, officials said.
Of the 636 passengers and 413 crew on board, 135 are Italians and 127 French, along with nearly 100 Austrians, 90 Swiss and 31 Britons.
The company says it is liaising with passengers' families via their emergency contact numbers, and has reached two-thirds of them. Contact has been made with the relatives of all the crew.
Families in the UK can call the company's emergency line on 020 7940 3300.
Authorities in the Seychelles earlier said that a plane had flown overhead and reported that the ship did not appear to be in danger.
The ship is at the southern end of the seas that are vulnerable to attacks by Somali pirates.
But a government spokesman told the BBC that attacks in the area had decreased in the past year as security improved.
The ship sailed with nine armed guards on board, and more are stationed on the French fishing vessel. Pirates in the area have never seized a cruise ship.
A government plane is also patrolling overhead.
Costa Cruises said that the ship sent out a distress signal when the fire broke out, and all passengers and crew not involved in fighting the fire assembled at the muster stations.
Most electric lights on board the ship are off as the batteries are being used to keep essential machinery going.
A facility on Costa Cruises' website allowing people to track the Allegro's position says that "data transmission is temporarily suspended".
The company says the Allegra received its regularly scheduled maintenance in dry dock in October 2011.
The Costa Concordia ran aground off the Italian island of Giglio on 13 January.
The Concordia captain, Francesco Schettino, has been accused of manslaughter, causing a shipwreck and abandoning ship before all those aboard were evacuated. He denies any wrongdoing