Related Clues:

• Hazard to navigation
• Boating hazard
• Steam (up)
• Airport delayer
• London atmosphere
• Visibility obstacle
• Measure of how high you are
• Makeup of some banks
• Pea soup, e.g.
• Pea-souper
• Feature of some horror films
• ___ machine
• Thick haze
• London weather
• Navigation problem