More than 80 migrants are missing, feared drowned after two boats sank in separate incidents in Greek waters.
Another fifteen bodies have already been recovered.
In the most serious incident, around 70 people are missing after a boat broke up and sank off the island of Kythira.
So far, 30 people have been rescued after scrambling ashore near the village port of Diakofti.
One resident described seeing the boat “smashing against the rocks” and people climbing up them to try and “save themselves”.
“It was an unbelievable sight,” Martha Stathaki said. “All the residents here went down to the harbour to try and help.”
Rescuers lowered ropes down to the seafront to help survivors climb up the cliffs to reach safety.
A nearby school has also opened to provide shelter for those who have been rescued, local officials said.
With many people still missing, navy divers are expected to continue searching the area on Thursday.
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Further east, a total of 15 bodies have been recovered by rescuers near the island of Lesbos after a dinghy carrying around 40 people got into difficulty on Wednesday night.
Five people were saved by the coast guard, and three others were found climbing a rocky ledge close to where the sinking happened.
Most migrants reaching Greece travel from neighbouring Turkey, but smugglers have changed routes in recent months to avoid heavily patrolled waters around Greek islands near the Turkish coastline.
Greece has toughened its migration policy in recent years and regularly carries out interceptions of boats at sea – a move which has been criticised by some human rights groups.
The country has repeatedly blamed Turkey for not taking sufficient measures to stop migrants from making the dangerous journey.
Kythira is some 250 miles (450km) west of Turkey and part of a route often used by smugglers to bypass Greece and head directly to Italy.