The Coast Guard said the boat capsized on Sunday in unclear circumstances while near Desecho Island in the Mona Passage.
A ferry en route to the Dominican Republic, the Kydon, reported spotting multiple people in the water and rescued two of them on Monday, it said.
Those aboard a recreational vessel, the Kiara, reported on Tuesday they had rescued two more.
The survivors, brought aboard the Coast Guard cutter Joseph Napier, were reportedly not wearing life jackets when rescued and showed signs of dehydration and sunburn.
The agency did not identify the survivors or their nationalities.