Swimmers and surfers were called out of the water at Cupsogue County Park in West Hampton at the west end of Dune Road when 5-7 shark fins were spotted.
The sharks were seen as close as 10 feet from shore.
The sharks were said to be about 15 feet long and were chasing bait fish along the shoreline and in the breakers.
No one was injured, but the sharks were the only ones who got to enjoy a full day at the beach.
The Suffolk County Parks Department will make a decision Wednesday morning on whether to allow swimmers back into the waters off Cupsogue and Smith Point Beaches.