The Blue Hole is undoubtedly Guam's most popular divesite.  It's a natural limestone vertical shaft formed millions of years ago which extends down into the reef.  The opening is approximately 35 X 25 ft.

The upper reef varies in depth from 20' near the cliffline, to 55-60 ft at the upper opening of the shaft.  From there it drops downward to 300+ feet.   The first opportunity to exit the shaft is at 127 feet.   It is common to see large pelagic fish below and as you follow the wall on the outside of the Blue Hole you probably will see more.

Gliding down the awe-inspiring shaft can get even the most experienced diver’s adrenaline up, so watch your descent rate and depth carefully. Soft and hard corals, sea whips, fish and eels can be seen inside the shaft.

Once out of the shaft, ascend to about 80 feet and follow the contour of the wall for a while.  Then ascend to the 60’ reef flat where there is a variety of hand-fed fish and several rock mounds covered with interesting corals and algae. Watch for large trigger fish and lots of schooling fish.

Divers should look very carefully underneath the rock formations slightly west of the  blue Hole as you'll find a resident moray eel or two, lionfish, leafish, and schools of snappers and rainbow runners there.

WARNING: Because of the incredibly clear water and "no bottom" conditions divers must use extreme caution and monitor their depth and time  carefully.

This reef can definitely have a current, so safety sausages or tubes should be considered mandatory and taken on every dive.

Some pix courtesy of Chris Bangs