Quicksands

Acts 27:17, probably the dangerous sandbanks and whirlpools in two gulfs on the African coast south of Malta; they were called the Greater and the Lesser Syritis, and were much dreaded by ancient mariners. The course of the wind by which Paul and his companions were driven, threatened to cast them into the Lesser Syrtis.

Source: ATS Bible Dictionary
Quicksands

Found only in Acts 27:17, the rendering of the Greek Syrtis. On the north coast of Africa were two localities dangerous to sailors, called the Greater and Lesser Syrtis. The former of these is probably here meant. It lies between Tripoli and Barca, and near Cyrene. The Lesser Syrtis lay farther to the west.

Source: Easton's Bible Dictionary