Reef formations that grow close to the water’s surface and shallow sea grass beds will make the water appear brown. Such areas should be avoided to keep from running aground and damaging both your boat and these sensitive habitats.
	Sand bars and shallow rubble areas appear white. These areas can be deceiving and may be much sallower than they appear. Navigate with caution around these areas.
	Green water usually indicates an areas free of shallow reefs or seagrass beds. Navigation of small, shallow draft boats in these areas is generally safe. However, larger, shallow draft boats should exercise caution. All boaters should carry and consult the appropriate NOAA marine chart.
	Deep water areas, such as the ocean side of a reef may appear blue. Navigation in these areas is free from hazardous contact with reefs or seagrass beds. Remember, however, that coral reefs rise abruptly from deep water so give yourself plenty of room to maneuver.

	Reef Light Towers - are prominent metal A-frame structures with a number posted on them.
Shoal Markers - are solitary steel I-beams, standing approximately 10 feet, usually with a diamond-shaped DANGER sign attached.
Many extensive shallow reef areas are marked by Reef Light Towers or Shoal Markers. You can determine where the shallow edge of these areas is located. Along the reef, there will often be a series of breaking waves. Along the edge of seagrass flats, you will frequently see a ripple effect or surface water texture change. Shallow sandbars will appear glassy.

Turn off your engine immediately. Do not attempt to use your engine to power off the reef or grass flat, which could damage your boat as well as these important habitats. If possible, raise your lower unit or outdrive and allow your vessel to drift free from the shallow area. IF you cannot drift free, radio Coast Guard, Sanctuary Patrol or Marine Patrol or VHF Channel 16 to provide you with assistance.

Coral Reefs are essential marine habitat that fish and many other marine creatures need to live, eat and reproduce. Corals grow very slowly, some at a rate of 2 centimeters per year. Boat groundings can instantly pulverize coral, leaving areas open to infection by disease and devastating a thriving coral reef community.

Damage to seagrass beds can be equally devastating. Seagrass beds act as a nursery and feeding ground for numerous organisms. They also filter excess nutrients and trap sediments, thereby providing the clean, clear water essential for coral reefs. By running aground or even motoring in very shallow water, boats can scar seagrass beds. These narrow sand channels can grow wider and wider, decreasing the seagrass bed’s ability to protect the reef and provide a healthy community for marine creatures.

• USE EXTRA CAUTION when there is extensive cloud cover, a glassy calm sea state, extreme sun glare or murky water. These are conditions when colors may not be apparent.
• Mooring buoys are located in the Florida Keys National Marine Sanctuary to keep boaters from damaging coral with their anchors. Some mooring buoys are located near extremely shallow reefs. Do not attempt to motor across a reef to reach a mooring buoy.
• Polarized sunglasses are very helpful in distinguishing water colors.
• For Key Largo National Marine Sanctuary, use NOAA chart #11462.
• For Looe Key National Marine Sanctuary, use NOAA chart #11445 or #11442.
• NOAA navigation charts are available at many marine supply stores throughout the Keys.
• For a complete guide to the charts avaiable for the Atlantic and Gulf coasts, contact NOAA's Charts & Publications Branch at (301) 436-6990.

Contact one of the Florida Keys National Marine Sanctuary Offices: