This article is intended to provide the already qualified Scuba diver with information which will help to plan dives in the waters of Guam, whether as a local resident or a visitor. Information is provided without prejudice, and is not guaranteed accurate or complete. Use it at your own risk.
Guam has some of the best dive sites in the world since there has been minimal tourist impact compared to other better known dive locations. Piti Bomb Holes has been built up as a tourist attraction allowing tourists to descend into an observatory where they can take in the beauty that has grown in a sinkhole. (The name "Bomb Holes" is a misnomer.) Divers may dive around this attraction and feed shoals of fish for the amusement of the tourists inside the subaquatic observatory as much as for the divers' own amusement.
While many of the dive sites can be reached by land, some of these entry points require a long walk over coral or a long surface swim. Also, because so much of the island is controlled by U.S. military bases, many of the dive sites are accessed by land through the military bases.
The list below are some of the dive sites in Guam.
North of Piti Bomb Holes
Gun Beach is the only Scuba dive site in Tumon Bay, the main resort hotel-tourism area. Most other sites, are about a 30-minute drive from the Tumon hotel district. This dive site is at the extreme North side of Tumon Bay, past the last hotel, and down a short dirt road which has a sign warning that the road is closed to the public. There are no facilities at the site, although it is within a 5-minute walk of the nearest hotel. Note that there is NO protected area of the shallows which are sufficiently deep to conduct the shallow-water dive lesson commonly given in "resort diving", although the site is nearly attractive in other respects. This beach dive is started and ended by walking in ankle-to-knee-deep water perpendicular to the beach, along a thigh-width pipe. At the wave-break zone, this pipe is at the bottom of a rip-current notch in the reef. The pipe has rough joints at intervals of about one yard, making it almost a perfect "ladder" to easily work back in toward shore against that outgoing rip-current. Once past the wave-break zone, the reef slopes off at a gentle 20-degree angle toward deep water. The shallowest portions almost reach the water's surface, while the deep end finishes in a sandy plain roughly 90'–100 feet down. Divers should confine their attention to the side of the dive site closest to the center of Tumon Bay rather than "away", because the "away" side is generally populated with dead corals and Crown of Thorns starfish. The "near" side, on the other hand, has excellent corals: candlesticks, brain corals, and antler corals. There are hand-shaped "spider" shells, an abundance of fish life, and an offshore permanent boat mooring.
Warning. This dive site has a risk of strong outflowing currents during falling tides so divers must take care to return with ample air in order to hug the bottom. The knuckled joints of the cable pipes are helpful in order to return against this strong tide, but only if the diver has enough air to get to them. It is best to study the tides and plan for an incoming tide at time of return until the diver becomes familiar with diving this location. It is recommended that interested divers join the local shore dive group at MDA or hire local guides.
Blue and White
South of Piti Bomb Holes / Apra Harbor
This walk-in site has more than 200 fish species as it is a marine park and breeding site for fish and invertebrates. Divers can see the healthy reef on the south side of the observatory, feed the fish and even snorkel around the observatory itself. A visit to the unique observatory fun for the non diving family members who can see you at a 20-foot depth.
The "American Tanker" is actually a large 300+ ft concrete barge. Recent information found on the internet indicates that in late 1944 the barges were loaded in Honolulu with war supplies, and then towed to Guam from Honolulu by the USS Bannock and Arikara. Later they were put into position on the Calahan bank by the USS Gear and sunk to provide a breakwater at the mouth of Apra Harbor. American Tanker pilothouse is at a depth of 40 feet/13 meters. Depth to the main deck is 60/20 meters and the ship has a list to the right (starboard side).
Family Beach, located near Outhouse Beach, is within Apra Harbor, thereby guaranteeing that during most weather it is divable. Unlike Outhouse Beach, it is fairly brightly lit, with moderately well developed corals and moderately abundant sea life. Parking is alongside a white sandy beach. From there, divers wade out on a flat, sandy/grassy bottom in knee-to-waist-high water until reaching a narrow (30' wide) canyon that runs parallel to the beach. Diving is typically done along near and far walls of the canyon, in 6'–30' of water. Care should be taken not to stir up the sandy-silty bottom of the canyon, in order to maintain good visibility during the dive. The primary reason that Outhouse Beach is a common dive site, while Family Beach is not, is that Family Beach's access is controlled by a private owner who may charge fees or deny access, whereas Outhouse Beach is not hampered in this way.
Like Outhouse Beach and Family Beach, Finger Reef is inside Apra Harbor, and therefore divable even when rough weather threatens to make most of Guam's divesites undivable. There, the similarity ends. Finger Reef is an extremely well developed reef wall along the opposite side of Apra Harbor, much closer to the Harbor's sea access opening. It is quite far from shore, and the nearby shore is part of a restricted-access military base, so almost all divers reach the site by diveboat. The reef starts at roughly 20~30' and drops off to roughly 60'. Dives are typically done as wall-dives, but not drift dives. Divers typically make their ascent and descent along the boat's anchor rope, and the boat is motionless during the dive. Because Finger Reef is full of sealife, protected by the harbor, relatively shallow, and near Blue Hole, it is a very popular second dive of the day after visiting Blue Hole.
Located in Naval Station on the western coast of Guam, Gab Gab Beach is in a restricted naval base so only military personnel will have access to Gab Gab Beach. The beach is great for snorkelers, and beginning and experienced divers. Divers can do a beach entry or come in off a boat. There are coral slopes and plenty of fish.
Gab Gab 2
Accessible as a shore dive past Gab Gab if you're in the military, short boat ride otherwise. Dive site is marked with a white buoy directly across from "Gab Gab" beach on ComNavMar Naval Base. Fish feeding areas are set up to get large amounts of fish to gather as scenery for a small tourist submarine ( "Atlantis" ) which makes trips through the area. Large amount of fish, a few lionfish and a rather large eel that hangs out by the feed bucket. Be careful around the Giant Trevally Jacks as they are known to bite fingers.
Outhouse Beach is a popular site for scuba certification dives. On a typical day, five to ten scuba schools' vans will be gathered at this site conducting Open Water certification dives. This should not, however, be taken as a sign that the site is exceptionally pretty. In fact, it is not. The steep beach is made of large pebbles. Underwater, there is little or no reef, and little sea life. Horizontal visibility underwater is between 10 and 20 yards. The main reason for its popularity with dive shops is that the site is within Apra harbor, virtually guaranteeing that even during inclement weather the site will be divable. In addition, the beach entry is particularly easy, with no sharp corals to walk over nor long surface swim. Family beach is at the end of the road past Outhouse Beach and a dive flag is required there.
To the west of the Tokai Maru lies a third huge shipwreck, the Japanese freighter Kitsugawa Maru - another casualty of the days prior to the US invasion of Guam in 1944. Torpedoed by the submarine USS Seahorse, she was towed into the harbor for repairs and, while at anchor, was attacked by bombs and rocket fire from raiding US aircraft, finally sinking when her engine
room exploded, tearing the ship in two and sending her into the depths where she sits upright on her keel at an average depth of 140 feet.
The 290-foot Cormoran lies in 120 feet of water on her right (starboard) side directly beside the Tokai Maru (which went down in 1943). The easiest way to reach the Cormoran (and dive on two ship from two different wars at the same time) is to follow the midsection hull of the Tokai over the side until you see the Cormoran at 80 feet. The hull of the Cormoran is intact. The engine room is easily accessible through the skylights, and most of the superstructure is relatively intact. Visibility averages 35–40', but can vary due to the tide and large ship traffic in the harbor. An average diving depth to see all of the port side would be 80-100 feet. Visibility averages 35-40', but can vary due weather and tidal flow in the harbor.
The Tokai Maru is a large ship, over 440 feet long. She rests in 120 feet with an 85 degree list to port (left). The shallowest part of the ship is the upper forward bridge area at a depth of 40 feet. A torpedo has blown a hole in the port #3 cargo hold, and this is undoubtedly the torpedo that sunk her. There is damage on the starboard bow, but this is believed to have been inflicted on the first attack in January 1943. The cargo holds contains remains of truck frames, beds, scrap steel, and miscellaneous objects. The engine room is huge, and both of her engines, catwalks, and panels are intact. The after-deck house in the stern of the vessel contains at least four unexploded depth charges, which are plainly visible from the top of the structure. DO NOT attempt to touch or move these depth charges. Visibility averages 35-40 feet, but can vary due to the tide and large ship traffic in the harbor. A good average diving depth to see all of the Tokai would be 60-80 feet.
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 is 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 feet (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.
Hap's Reef is a well-developed coral mound several hundred yards offshore, in roughly 30'–40' of water, with flat terrain and shallow sandy valleys surrounding it. It is generally accessed by boat, and is a favorite 'second dive of the day" after diving the nearby Blue Hole.
When you enter the water set your compass to the buoy and there will be a ledge with a 6-foot drop-off. Just hop in here and descend and head toward the buoy. Along the way the clarity will not be great (due to the water treatment plant). Just keep swimming and eventually it will clear up and you will run right into a reef, do not go around this reef instead swim over it. On the other side of this reef is where you want to end up. Some of the features you will see here include a number of swim-throughs. Some of them are extremely large while others you are going to have to squeeze through. The aquatic life is very abundant, spinner dolphins have been seen at this site, as well as lion fish and a huge assortment of other reef fish. This is a very easy and fun dive and the reef is in great shape.