The authorities said the total number of corpses taken from the sea has now reached 31.
Dozens of people were killed off the Arabian Sea shore on Wednesday after defying a ban on swimming during the monsoon season.
The bathers were among thousands who had taken to the beaches to celebrate the Eid-ul-Fitr holiday, which began on Tuesday and continues until Friday.
"We have pulled out more dead bodies from the sea and the total number of the people who died after drowning in the sea has now reached 31," Shoaib Ahmed Siddiqui, Karachi's top administrator told AFP.
Officials said they could not rule out finding further bodies in the water.
"We will continue the search operation as we are still not sure about the number of missing picnickers," Siddiqui said.
On Wednesday, senior police officer Ibadat Nisar said cops had discovered three bodies washed up at the upscale Clifton beach on Wednesday evening, which prompted a wider search operation that was suspended overnight and then resumed Thursday.
Navy helicopters and speed boats were leading the search operation, both along the coast and in the open ocean.
"Our teams are looking for the bodies up to 15 nautical miles (from the shore)," commander S. M. Kamran, the spokesman of the navy told AFP.
"But beyond that our big boats are also watching out for any stray body," he added.
Several ambulances were seen on the beach where the relatives of some of the missing anxiously waited for word of their loved ones.
Faiz Rehman, 32, said he and his younger brother had come to the beach on Wednesday to go for a swim along with two friends who were now missing.
"As we were swimming in the sea, I noticed the waves getting bigger and more rough, and I got scared and started swimming back," he said.
"I also called my brother and friends to swim back to the shore. My brother returned but my two friends were still swimming. As the waves got bigger I lost sight of them."
Thousands of residents regularly throng Karachi's beaches on public holidays, which has few public parks available for picnics.
But safety standards are very low with the few lifeguards on duty often unable to exert any authority.
Karachi, a teeming city of 20 million people, is Pakistan's economic hub and is regularly wracked by political and ethnic violence.