11 Mile Reef


This reef is about 300 X 100 yards and can be one of the most exciting dives on Guam. Or, and totally depending upon if there isn't any current, it can also be one of the most boring because all of the bigger fish leave. 

It's located more than 11 miles southwest of the Agat marina. The top of the domed-shaped upper reef area, which is quite small, is at 80' and gradually slopes to the sea floor at about 90 feet. There is a very good probability of seeing sharks, schooling barracuda, rays and large schooling fish on this dive if there s current there.

Pilot whales and spinner dolphins are frequently seen on the way to this site. It can be a rocky boat ride even on the best of days so divers that have a tendency to get sea sick probably shouldn't even attempt to go.

CAUTION: This is one of the few dives on Guam that a reef hook is mandatory. Medium to strong upper reef currents and swells can make this a challenging dive. Divers should be very experienced for these conditions and thoroughly briefed. it is very easy to get swept off the upper reef due to it's small area and in heavy currents. It's almost impossible to swim back to it. Divers should be very familiar with deploying a safety tube at depths.


Rays are sometimes referred to as the birds of the sea. They are amazing disc-shaped creatures that gracefully swim about the ocean. All rays are characterized by a unique spherical body shape with a raised head and eyes set to the sides. Their nostrils, mouth, and gill slits are located on the underside of their body. They are completely composed of cartilage; they have no bones.

The most striking feature of rays, however, is what is known as cephalic fins, the wing-like appendages that allow them to "fly". Rays are also equipped with a whip-like tail that can have a barbed spine, capable of inflicting a painful wound.

Rays learn to evade predators by spending much of their time on the sandy bottom, and try to conceal themselves by flapping their pectoral fins to throw sand on their body.   Rays are bottom feeders, eating crabs, conch, oysters, crustaceans, plant worms, plankton and some fish. They have powerful jaws and grinding teeth.

Give them the space they deserve.  They pose no threat to us.

Depth Ranges: 80-150'   Exp Level: Very Experienced  Access by boat    Avg Vis: 70-120'   GPS: 13.13.2N, 144.27.02E