The Blue Hole is one of Guam's most popular dives. The "Blue Hole" is within 30 yards of shore. However, the shore it's near is a towering, jagged cliff on a military base. Therefore, it's typically accessed by divers via boat. The Blue Hole is, like Saies Tunnel in Palau, a wide tunnel from shallow to deep points within a submerged wall. The hole's shallowest point is within a few yards of the edge of an extreme vertical dropoff, and lies in about 40' of water. The tunnel below it is a straight vertical plunge to the extreme limit of recreational diving depths, roughly 110' (depending on the tides). The tunnel is roughly as wide as a passenger van. There is a permanent boat mooring at the top of the tunnel, and descent is usually made along this anchor rope. The dive site is not particularly well endowed with corals. For a good coral reef, boats typically make a second, shallower dive at nearby Hap's Reef (outside Apra Harbor) or Finger Reef (inside Apra Harbor). Horizontal visibility is typically 20 to 30 yards or better. Caution should be taken regarding depth and nitrogen accumulation, since the extreme water clarity and extreme depths along the wall can easily cause unprepared divers to dive deeper than they'd intended.
Diver Joe June 11th, 2017 - 9:24:Great dive, but make a plan and follow it. My first time in the Blue hole of Guam (last week) was almost my last dive. I snorkeled till I got directly over the opening, let the air out of my BC, and dropped like a rock.. flew right past my 2 buddies at 120'. I didn't notice the opening at 125'; it was a super clear day, so I can only guess I was facing the shore checking out the wall and my gages as I descended. My eyes were glued on my pressure gage, but the light got a little too dim for my depth gage. The whole time the bottom looked like it was "right there", so I figured I'd touch bottom and then go back up immediately. As I got close to the bottom I saw an opening letting in light on the bottom sand/rocks, but it was not the 125' window. My bubbles started to sound like little bells, so I knew not to hang out once I hit bottom. After 30 seconds checking out the cool purple and blue wall rocks, I left bottom only to find out it was going to take some good kicking to get up the first 50ft. Going up only as fast as my bubbles, my head was surrounded by a whirlpool of ever increasing bubbles, all ringing like little bells the first 100ft. Once back at 60ft, I stopped and took inventory of the dive. 1500 PSI remaining, Max depth 200+(tattle-tale past the 200 limit). I compensated for going way deeper than I planned by staying 5 mins at 60', 10 at 40' and 20 at 20', then hanging out under the boat at 10' till I was almost out of air. Went back today and set the limit at 200'; only stayed long enough to make sure my buddy wasn't getting sucked in at 225'. Once I saw him heading up, I contoured up the outer wall. This time, on the way down, I saw the window at 125' and it looked open all the way to the bottom. I didn't see the shaft I went down last time. So, I'm kinda confused where exactly I wound up last time. I had only minimal narcosis at 200' - nothing compared to the dive last week.