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Anchoring in the Florida Keys

The right way to anchor in the Florida Keys!

Mooring Buoys for Diving

Many divers use the state of the art mooring buoy system in the Florida Keys National marine Sanctuary.  It is available to anyone that wants to use it and it is always a good idea when you are in an environmentally sensitive area.  In the Marathon area, you will find these at Coffins Patch and Sombero Light.

General etiquette applies to these buoys.  The buoys are on a “first-come first-served” basis, but it is important that you use the buoy, do your diving, and vacate so someone else can enjoy a dive. Remember this buoy system is set up for diving and not fishing.  It can be illegal to fishing in these areas.

Hooking up to the Thunderbolt Wreck

“The Thunderbolt has no marker. The depth of the water is 120′. There are two mooring buoys, one on the bow and one on the stern, but they’re under the water at 15′ and 20′ down. There’s a metal ring on top of the buoys. Someone will need to free dive down with a line from the boat and pass it thru the ring, then cleat it off on your boat. This is a protected area. Special rules and regulations do apply. The saying is “Take only photos and leave only bubbles.” It’s located 5 miles southeast of Vaca Key and one mile south southwest of red channel marker #20.”

In the picture above, the Captain Hook’s Dive Crew is getting ready to install the mooring ball for the Thunderbolt.

Proper Anchoring Protects the Florida Keys


Anchoring the right way in the Florida Keys is critical to protecting the underwater marine environment.  An poor anchor job can cause tremendous damage to the reef and destroy something that took thousands of years to grow and develop and turn it into rubble.


There are several types of anchors on the market and can be seen in the picture above.  Each anchor is designed for a specific purpose.  The anchors that are provided on your rental boats are general purpose Danforth anchors.  They are best suited for most of the anchoring requirements in the Keys for that size boat.

Anchor System

Your anchoring system consists of the anchor, shackles, a short length of chain, and then the anchor line.  The anchor is shackled to a length of chain about 4 to 6 foot in length.  The chain weight helps to get the anchor set.  This means getting the blades of the anchor to sink into the ocean bottom to hold the boat in its position on the surface.  The line is usually some combination of nylon braid usually 100 to 150 foot in length for the rental boats.


Anchoring Location

The larger the boat or the deeper the anchoring location the more anchor line is needed.  You need enough line out to get the right angle on the anchor line to allow the anchor to set.  If the line is too short, the anchor will not set and will keep releasing skipping alone the bottom. Too much line can also be a problem, because the line can hang up on any number of things in the ocean.  There are all sorts of theories out there as to the right ratio of depth to line length.  The illustration above shows a 7 to 10 times the depth to establish the length of the line.  Some people use as little as  3 times the depth.

The most important thing to consider is your impact on the environment.  In an environmentally sensitive area such as the Keys, the wrong angle of line can break off coral heads and damage reefs and as the operator you can be fined for this type of damage.


Always make sure you anchor into the sand and there is enough distance and angle for the anchor line to avoid impacting the reef.  The best way to do this is to select a location that is up current of where you want to fish or dive.  Place the anchor in the sand above your desired location.  Then as the current takes the boat back to the desired location, you will be right there to enjoy the diving, snorkeling or fishing.