quicksands

Boyd’s Bible Dictionary:

The Syrtis, greater and lesser

Concise Bible Dictionary:

The Syrtis is a quicksand on the north African coast between longitude 10° and 20° E. (Acts 27:1717Which when they had taken up, they used helps, undergirding the ship; and, fearing lest they should fall into the quicksands, strake sail, and so were driven. (Acts 27:17)). There are properly two, called the major and the minor; it would have been the major one on the east of the bay that they were in danger of. It is now called the Gulf of Sidra.

Strong’s Dictionary of Greek Words:

Number:
4950 (find all occurrences in KJV Bible)
Greek:
σύρτις
Transliteration:
surtis
Phonic:
soor’-tis
Meaning:
from 4951; a shoal (from the sand drawn thither by the waves), i.e. the Syrtis Major or great bay on the north coast of Africa
KJV Usage:
quicksands