Related Clues:

• Driving danger
• It's a great barrier
• Nautical hazard
• Cause of many an accident
• Oceanic whirlpool
• River hazard
• Contrary current
• Haze
• London weather, often
• Visibility problem
• What goes around
• Great Barrier --
• Navigation hindrance
• Naviga-tion hindrance
• Ship's nemesis