According to witnesses, the child was swimming when she went underwater and did not resurface.
Three swimmers have died, and several others had to be rescued due to rip currents at Jersey Shore over the weekend.
The man was at the lake with family, friends.
Robbins is believed to have fallen overboard from a sunset cruise near Nassau, the Coast Guard said.
They called on the company to modify or eliminate dams altogether.
The family of Antonio Roman says he risked his life to save a woman and child when a group on inflatable tubes went over a Duke Energy dam along the Dan River.