Reference: Quicksands

The Syrtes, Major and Minor, are situated on the N. coast of Africa, in the wide bay between the headlands of Tunis and Barca. They consist of sandbanks occupying the shores of the Gulf of Sidra on the coast of Tripoli, and that of Gabes on the coast of Tunis or Carthage. They have been considered a source of danger to mariners from very early times, not only from the shifting of the sands themselves, but owing to the cross currents of the adjoining waters.