Related Clues:

• Boating hazard
• Peril at sea
• Great Barrier, e.g.
• Besiege
• Site of a shipwreck, perhaps
• Ominous forecast
• Squall
• Tornado or hurricane
• Lagoon creator
• Attack en masse, as a castle
• Lightning producer
• It might be just below the surface
• Dark-clouds bringer
• Word with 119-Across
• One can be tracked