While Guam is an extremely popular location for holidays for people from many Asian countries, especially Japan and to a lesser extent, South Korea, it is not a place high on the "must do" list for Australians. Virtually the only Australians who visit Guam are scuba divers, and even then, most only visit as a consequence of their aim to visit other locations. For many Australian divers, the only time they visit Guam is when travelling to or from Chuuk or Palau.

Guam is not all that big, it is only just over 40 kilometres long and up to 16 kilometres wide. There are coral reefs all around the island and as such, there is a lot of dive sites around Guam. However, there is only one location that visitors can dive as charter boats/dive shops only run out of one location, Apra Harbor.

Apra Harbor is the only protected anchorage in Guam and is located at the westernmost part of the island. It is not a huge harbour (in fact is appears to be an artificial harbour with the northern side man-made), but big enough to be home to a US naval base (with nuclear submarines). Inside the harbour are a number of wrecks, the best known being the World War I German ship SMS Cormoran and the World War II Japanese ship Tokei Maru.

Looking towards Orote Point from Blue Hole	Another shot of Orote Peninsula

Most of the diving seems to be not on the wrecks, as when we dived there the operator had not dived the above two wrecks for a long time, over a year.

Outside Apra Harbor there are a number of dive sites quite close and there are even a couple of sites inside the harbour. This article is about the most popular site outside the harbour, Blue Hole.

Although the harbour is man-made, the southern headland is a very dramatic geographic feature called Orote Point. The cliff here is as high, if not higher, than North Head in Sydney Harbour. After heading across the harbour, the dive boat turns left and heads south. The dramatic cliff runs for quite a while along this section of coastline.

Blue Hole is located only a kilometre south of the harbour at GPS Reading N13° 26' 11.4" E144° 37' 33.9" using WGS84 as the datum. At this location there is a mooring. The mooring is in about 18 metres on the top of the reef wall. As you have probably worked out, Blue Hole is a hole in the top of the reef that drops down and exits onto the wall.

Blue Hole as you drop down from the mooring	Looking back from deep inside Blue Hole

Once you enter the water, you descend down the mooring line and straight away you will see the Blue Hole. It is about 20 metres long and 10 metres wide. At 18 metres you enter the hole and straight away you can see the bluish glow coming from the exit below. As you head down, look back up at the other divers following you. You can get some great photographs if you are careful with your exhalation bubbles.

The hole drops to about 40 metres before you can exit. The exit is huge, the opening extends all the way to the bottom of the hole at about 55 or perhaps 60 metres. The wall here is shear and runs back up to the reef top at 18 metres. The bottom of the wall is at least 80 metres from what I could see.

Kelly McFadyen approaching the exit of Blue Hole	A sea whip on the wall just outside of Blue Hole

Normally there is a current so you drift with the flow and your boat will pick you up when you surface. On my dive here the tide was running back towards the harbour. Outside the hole the wall has some nice gorgonias, but mostly these are deeper than the depth you will need to be at for the dive. Some of the gorgonias are huge, probably two metres across. However, other than that, there is little live coral or sponge life to be seen on this dive.

As the visibility here is normally excellent, at least 30 metres, you will be able to see a long way up and down the wall. As such, it is easy to see what is coming up as you drift along and change direction to make sure you see all the feature of the site. The current is not extremely strong and you could swim against it if you wanted to.

Kelly with some clownfish on the wall	One of the huge boulders back up on the reef top

You will have to start ascending almost as soon as you exit the hole as you will have reached about 45 metres, meaning you only have about eight minutes before you will enter decompression. If you are careful, you can stay out of decompression by gradually ascending.

The wall seems to be patrolled by reef sharks. On my dive here I saw a white-tipped and a black-tipped reef shark. Along the wall there are moray eels, some anemones and clownfish and other smaller fish.

After about 10 minutes you will still be at 30 metres but soon have to come up onto the top of the reef. A few minutes later you will be at 20 metres and this is the top of the wall. For the next 20 minutes the depth stays roughly the same.

Some more boulders on the reef top	A strange, thin rock near the boulders

As soon as you hit the top of the wall you will see that the reef top is very wide, at least 30 metres. Back towards the shore it gradually rises back up towards the surface. On the top there are lots of huge boulders. Some of these are as big as a garage. In some places the boulders are bunched together and form small swim-throughs.

After about 35 minutes you will need to move closer towards the shore so that you can get a bit shallower. The wall here is a gradual slope. In places along here there are some small holes and cracks. Check them out, we found a mantis shrimp in one. There are also more sharks patrolling this part of the reef.

Finally, you will need to start your ascent. To do this you will have to swim out at right-angles to the reef to get away from the shore. This is so the dive boat can safely collect you. Do a safety stop as you swim out, but make sure you do not go too far. Your guide should have a safety sausage to send up, but if you have separated from the guide, send up your own.

Kelly at the entrance to a swim-through formed by two boulders	A mantis shrimp on the shallower reef

This is a nice dive, with a very exiting start, a great vertical wall and some shark-life. It also has excellent visibility. It is a pity that there is not more coral and fixed marine life.

Probably the best available reef dive in Guam done by the dive shops.

I dived with Micronesian Divers Association but did not use their own boat. As they had a lot of divers on the days we were diving with them, they sub-contracted the boat for us from someone else. I can recommend them as the operation seems pretty good.

VIDEO

Video shot by Kelly McFadyen during our November 2011 trip to Guam.