Some 126 people have been rescued by Somali fishermen from the Gulf of Aden after human traffickers reportedly forced them into the sea at gunpoint.
The migrants, mostly from Somalia and Ethiopia, said they had set off from northern Somalia a week ago.
They said their boat had developed engine trouble and drifted for days before the people smugglers forced them into the sea. Six people are missing.
The BBC's Peter Greste says the scale of this incident is rare.
But our correspondent says stories of human traffickers forcing migrants into the sea are not uncommon.
The coast guard from the semi-autonomous region of Somaliland spotted the first survivors floating in the water on Sunday.
They said the boat had originally set off from northern Somalia with 135 people on board, hoping for a better life in the Middle East or Europe.
Such migrant crossings normally head for Yemen.
The mayor of Laaso Suarad, the town which organised the rescue, told the BBC they dispatched a flotilla of fishing boats to search for more survivors.
Eventually they found 126 of them clinging to bits of driftwood and utterly exhausted.
The search has also found three bodies.
The UN and the Red Cross are helping the survivors with food and medicines.
Somaliland is a relatively stable part of Somalia, which has declared independence from the rest of the war-ravaged country.