1) Bank 2) Boating hazard 3) Can be exposed at low tide 4) Danger for a riverboat 5) Dune 6) Riverboat threatener 7) Shoal 8) Shore shoal sight 1) Bank 2) Shoal 
[n] - a submerged bank of sand near a shore or in a river
noun a submerged bank of sand near a shore or in a river; can be exposed at low tide