Twelve South African divers arrived on the Indian Ocean island, Zanzibar Sunday night, to try to free the bodies believed to be trapped inside the hulk of the MV Spice Islander, which sank early Saturday, Zanzibar police said.
Rescuers have managed to save 619 passengers out of the more than 800 on board the severely overloaded vessel which was on its way to Pemba from Unguja, the main island in the Zanzibar archipelago.
The most recent official toll put the number of dead at 197. Police spokesman Mohamed Mhina on Sunday ruled out finding any more survivors.
Efforts to retrieve bodies have so far been hampered by a shortage of divers. Those that have been recovered have already been buried by families in cases where they could be identified. The government has taken charge of burying unidentified remains.
The rapidity of the burials was in accordance with Islam, the religion of the overwhelming majority of the population on Zanzibar.
Police spokesman Mhina said the morgue in the main hospital on Unguja was not big enough to deal with a tragedy on this scale.
Zanzibar President Mohammed Shein was to lead prayers for the victims and their families in the island's capital Stone Town later Monday.
Some angry survivors accused port and ferry officials of having ignored the protests of passengers that the vessel was overcrowded.
Those on board included families returning home after the holidays to celebrate the end of the Muslim holy month of Ramadan.
Passenger numbers are difficult to establish as no reliable passenger lists are kept and overloading of ferries is commonplace in the region.
Zanzibar Minister of State for disaster management Mohamed Aboud Mohamed on Sunday told journalists the vessel should have been carrying no more than 600 people and 500 tonnes of cargo.
A three-day period of national mourning for the disaster started Sunday. Tourism is the main foreign currency earner for Zanzibar, famed for its white-sand beaches and historical buildings in Stone Town, listed as a world heritage site by UNESCO, the United Nations cultural organisation.
The archipelago lies off the coast of Tanzania and has semi-autonomous status. No foreigners have so far been reported either among the victims or the survivors of the disaster. Pemba lies some 80 kilometres (50 miles) northeast of Unguja.