This is an account of my fifth trip to the Great Barrier Reef and the Coral Sea aboard the Undersea Explorer. The Undersea Explorer mixes research and recreational diving for a truly fantastic experience. It is one of the few vessels that makes regular trips to Osprey Reef in The Coral Sea. For more information about the Undersea Explorer, please see their website at

This year there was only two of us in our "group", Tim Everest and me. There were 18 other guests plus the crew of Neil (Skipper), Jaap (Engineer), Brendan (Dive Master), Karl (Marine Biologist), Ragini (Chef) Owen (Researcher) and Kathy (Hostess). Kathy was from Colombia, had got her marine biology bachelor degree in Costa Rica and was now doing her masters at James Cook University in Townsville. The researcher onboard was Owen O'Shea who is doing his marine biology honours project (at James Cook University) into fish cleaning behaviours, including manta rays. One of the other guests, Jess, had just completed her marine biology honours at my alma mater, University of New South Wales. It has been nearly 30 years and yet a couple of staff from my time are still working there.

The Trip

Day 0: 26 May

After arriving in Cairns at around 1:30pm, we (Tim and I) caught the bus to Port Douglas, arriving just before 3pm. After dropping our luggage off at the Undersea Explorer, we headed into town to shop for supplies. At around 4:30pm we headed back to the boat to "check in" to our cabins and register for the diving. We headed up to the Thai restaurant for dinner and were back to the boat at around 7pm.

Neil (the skipper) gave us the boat introduction at around 7:30 pm followed by an introductory talk by Brendan on the research done on Undersea. At around 9:00 pm the boat headed out to sea. Our adventure was truly beginning. As the seas were quite calm, I took the opportunity to get the computer camera gear ready. This only took around an hour and I was able to head off to bed knowing I was ready for the first dive in the morning.

Day 1: 27 May - Ribbon Reef #10

After a light breakfast we were given an introductory dive briefing by Brendan. The briefing basically set the rules and guidelines for all the dives on the trip, including buddies, no decompression diving (Queensland law) and other safety aspects.

The first dive of the trip was at Challenger Bay which is at the southern end of Ribbon Reef #10. Challenger Bay is a sandy area with small coral boulders next to a reef flat. In the deeper sand areas (around 12 m) there were garden eels and shrimp gobies. I saw a number of pipefish through the dive. Some were on the sand and others on the bommies. (Dive details << indicates photographs included in dive details)

Christmas tree worms, Spirobranchus sp., at Challenger Bay.

The first dive was followed by a cooked breakfast which really hits the spot after a dive. This was going to set the scene for the fabulous food we'd be having on the trip.

The second dive was at Lighthouse Bommie which is just north of Challenger Bay and also on Ribbon Reef #10. This bommie is a pinnacle in around 25 metres of water. We descended to the small bommie beside the main bommie and then circled around the pinnacle in a clockwise direction. Among other organisms, the site had a number of nudibranchs, two turtles and some longnose hawkfish. (Dive details )

Nudibranch, Chromodoris elisabethina, on Lighthouse Bommie.

Every dive should get followed by a meal and the second dive of the day was no different as it was followed by lunch. If we weren't getting so much exercise diving, we'd be putting on weight with all this great food.

The third dive of the day was at The Cod Hole at the northern end of Ribbon Reef #10. The Cod Hole is famous for its larger and friendly potato cod. It was also the first site on the Great Barrier Reef to become protected. Like Challenger Bay, this site has large sandy areas with coral bommies. (Dive details )

Regal angelfish, Pygoplites diacanthus, at The Cod Hole.

The last dive was a night dive at The Cod Hole. The highlight of the dive was a slipper lobster. While these animals are not all that uncommon, I had never seen one before. I also saw the proboscis of an echuran (tongue worm). I have seen these frequently on night dives in Sydney but not on the reef until now. (Dive details )

Slipper lobster, Parribacus antarcticus at a depth of around 5 metres on the night dive at The Cod Hole.

After dinner we headed off to the Coral Sea. The boat left at around 10pm and we sailed all night.

Day 2: 28 May - Osprey Reef

After a fairly rough night we finally arrived at Osprey Reef at around 8am. Osprey Reef is in the Coral Sea around 180 km (100 miles) from the Queensland coast and around 120 km (70 miles) from the outer Great Barrier Reef and continental shelf. It is a sea mount left over from an extinct volcano. The water depth away from the reef is more than 1000 m and the walls of Osprey Reef are quite steep.

The first dive of the day was at Admiralty Anchor. This site on the western side of Osprey Reef is so named for an old style anchor that can be seen on a swimthrough at the site. No-one knows how the anchor got to be where it was. The bommies in the area are quite steep and there is a level area at around 30m. If you go over the edge it is very steep and the walls disappear into the abyss.

The dive was interesting, as usual. We spent a bit of time between 20 and 30m where there is still a lot of life, including many light dependent corals such as Acropora, Montipora and Pocillopora. We slowly worked out way up to the entrance to the swimthrough which is at around 18m. Tim and I swam through to familiarise ourselves with the cave as we'd be back later in the night to see the flashlight fish. The exit to the swimthrough is in around 8m and brings us out at the rear of the main bommie. We spent the rest of the dive behind and then on top of the main bommie which is in around 5 metres of water. On top, Karl pointed out a very small stonefish, Synanceia verrucosa. While it was unmistakable as a stonefish, it looked quite different to the adults I have seen previously. (Dive details )

Juvenile reef stonefish, Synanceia verrucosa, on top of the main bommie at Admiralty Anchor.

The first dive was followed by a hot breakfast.

The second dive was at the northern end of Osprey Reef known as North Horn. Like Admiralty Anchor, this site is quite deep with gentle slope between 20 and 30 metres and then a cliff edge going into much deeper water. We started the dive at around 30 metres and there is even more life at this depth here than there is at Admiralty Anchor. In addition to all the corals, there was a carpet sea anemone, , at 30 metres. Between 20 and 30 metres we saw a large number of red firefish, , mostly in pairs and single dottybacks, . We finished the dive at the edge of the reef in 5 metres of water for our safety stop. (Dive details )

A pair of red firefish, Nemateleotris magnifica, at 22 m at North Horn.

After lunch, we did our third dive of the day which was a drift dive down the western wall of Osprey Reef to North Horn. It was a live entry from the boat and we descended to 23 metres on the wall and then drifted north with the current, ascending along the way. Areas of the western wall are literally covered with brightly coloured soft corals and sea fans. It is a beautiful site. At times the current was quite strong which was disappointing as I would have like to have spent more time marvelling at the sights. The dive finished at North Horn and as always we did our safety stop on the reef at 5 metres. (Dive details )

After some afternoon tea a few of the guests went out with one of the crew (I can't remember who), to set the nautilus traps for the night. The two traps are very basic and made from chicken wire. They have a conical entrance that lets the nautilus into the trap but they can't get out (at least not in a hurry). The traps are baited with chicken or something similar and lowered over the edge of the reef on rope that is 300m long. This means the traps will end up in at a depth anywhere from 100 to 300 metres depending on the currents.

We had a break we were ready for the night dive. This fourth dive of the day was back at Admiralty Anchor. The two main attractions for the dive were the large basket star which is almost always visible on the third bommie south from the mooring; and the flashlight fish in the cave of the swimthrough. My first two night dives at Admiralty Anchor (in 2002 and 2003) I had no trouble finding the basket star, but on the more recent trips (2005 and 2006) I had lost my knack. For this reason we followed Karl to the bommie so we'd be sure to see it and sure enough we did.

After the basket star we headed back to the swimthrough. We had to wait a few minutes as other divers were in there but then we made our way in, got settled and switched all our lights off. Sitting there in the darkness, it didn't take long for our eyes to adjust and then to be surrounded by small flashes of blue light. This was the flashlight fish (family Anomalopidae) that have a light organ beneath each eye. The organ is powered by symbiotic bioluminescent bacteria and the fish can turn the light on and off by opening and closing a sort of eyelid. It is quite amazing to watch the flashes as they move around.

We spent a few minutes with the flashlight fish and then headed out of the cave. Tim and Padalis continued through the swimthrough and I went back out the entrance. We met up at the front of the main bommie and spent the rest of dive swimming around it. (Dive details)

Dinner was served after the night dive and we spent a relaxing night at Admiralty Anchor.

Day 3: 29 May - Osprey Reef

First thing in the morning, Carl and Team Deutschland went out in the tender to retrieve the nautilus traps. It was a pretty successful haul with 26 animals in the two traps, including one very small animal and two recaptures.

The first dive of the day was at Raging Horn. At the site there is a manta ray cleaning station and most dives here encounter one or more mantas. Unfortunately, there were none there for us to watch. After waiting near the cleaning station for nearly 10 minutes, we ascended to continue our dive on the west wall of Osprey Reef. (Dive details)

The second dive of the day was a drift dive along the east wall of North Horn. The east wall is very different from the west wall and there are far fewer sea fans. It is still an interesting dive with many schools of Pseudanthias along the near vertical wall. We finished the dive near "the pulpit" (see next dive) where I sat still in an attempt to get some photographs of some of the fish. (Dive details)

The third dive of the day was the "Shark Attract" at North Horn, Various pieces of fish are placed inside two milk crates tied together. This brings the sharks in, but does not allow them to feed. All the divers get into the water first and position themselves around "the pulpit". The pulpit is a bommie surrounded by a reef wall that makes a kind of natural amphitheatre which allows the divers to view the sharks as they come in to attempt the get the food. Even before the food hits the water, there are a large number of sharks in the area. The visibility of the water was not great so it is hard to estimate exactly how many sharks there were, but I counted at least 10 grey reef whalers, , and even more white-tip reef sharks, .

Once we were all in position, Jaap and Brendan brought the milk crates with fish down to the pulpit where they secured it. We all watched as the sharks came in to have a go at getting the food. Every now and then a shark would be successful in getting some food from the crate. They would swim off with their prize being closely followed by 4 or more other sharks all vying for a piece. Each buddy pair were given the opportunity to get close to the pulpit and have a more intense look at the action. This also allowed better opportunities for photographs.

When it was all over, the food was taken back to the boat and we dispersed to complete our dive around North Horn. (Dive details)

Between the third and fourth dives of the day, Karl enlisted the support of a number of the guests to measure and tag the nautilus that had been caught and recovered that morning. This is part of the ongoing research that Undersea undertakes. On each trip to Osprey Reef they measure and tag as many nautilus as are collected in order to get a better understanding of the population of nautilus at Osprey Reef. At this point Osprey Reef is not protected and there is nothing (other than distance) stopping people from collecting these amazing animals for the shell collection trade. Tagging involves engraving a number on the shell, colouring the engraving black and painting with nail enamel to protect the engraving. It is believed that the engraving does not affect the animal at all and the recapture of previously tagged animals supports this. The nautilus are released back to Admiralty Anchor in the evening after they have been measured and tagged.

Nautilus processing.

Karl measures a nautilus while April (left) looks on. Jess (right) watches the nautilus in the tank awaiting the process. In the foreground an already engraved nautilus is being dried before being returned to the holding tank.

The fourth dive was a night dive at Admiralty Anchor. This was a relatively short dive as we had already seen the basket star and flashlight fish the previous night. (Dive details)

The weather was due to close in and so our time at Osprey Reef was at an end. It would have been too rough to stay for another day. Shortly after dinner we pulled up anchor and headed back to the Ribbon Reefs. It was a rough night, but sleep was the best solution to avoid the pounding seas.

Day 4: 30 May - Ribbon Reef #10

We arrived back at Ribbon Reef #10 just after sunrise and had a light breakfast.

The first dive of the day was back at The Cod Hole. We checked out some of the deeper areas and this meant it was a relatively short dive. We did see a number of anemones with anemonefish in the shallow water. (Dive details )

A barrier reef anemonefish, Amphiprion akindynos, at 16 m at The Cod Hole.

The second dive was a revisit to Lighthouse Bommie. This was almost a repeat of the previous dive to this site although I did see a few different things, including a stingray and an adult emperor angelfish, . (Dive details )

A longnose hawkfish, Oxycirrhites typus at 14 m at Lighthouse Bommie.

The third dive was at Pixie's Pinnacle. This site is quite similar to Lighthouse Bommie. The base of the pinnacle is in around 20 metres of water and as with Lighthouse, we descended to the base and swam around the pinnacle in a clockwise direction. One of the sights at Pixie's is a couple of flame file shells, Lima sp., in a hole. They can be hard to find so Brendan was going to leave a torch outside the hole to make it easy for everyone. Unfortunately, one of the guests removed the torch and we never found the hole. I did see a couple of lionfish, pipefish and a painted crayfish, so it wasn't all bad. (Dive details )

A double-saddle butterflyfish, Chaetodon ulietensis, at 14 metres at Pixie's Pinnacle.

The night dive was also at Pixie's Pinnacle. Tim sat this dive out, so I went with Padalis. I'm not sure how I did it, but the very first place we hit the bommie on the way down was where the two flame file shells were, so I got to see and photograph them after all, The other interesting thing about the dive was to see all the corals with their polyps extended. During the day you really only get to see a drab coral, but at night they show their true beauty. I also saw a number of banded coral shrimp, . I had a nasty experience towards the end of the dive when I accidentally placed my finger on a sea urchin. The spine went into my finger and broke off. The pain was quite intense initially and I was worried there may have been some toxin. Fortunately, the pain subsided quite quickly and I was able to complete the dive. (Dive details )

One of many expanded Tubastraea sp. colonies seen on the night dive at Pixie's Pinnacle. This one was at 11.5 metres.

Day 5: 31 May - Ribbon Reefs #5 and #3

Overnight we headed south to Ribbon Reef #5.

The first dive was at Clam Gardens. This is another sandy area with a number of bommies and, as the name suggests, has quite a few giant clams, Tridacna gigas. Some of these clams are enormous at over one metre in length. Cuttlefish are often seen here, but unfortunately we saw none. I did see three adult six bar angelfish, , one single and a pair. (Dive details )

Six-bar angelfish, Pomacanthus sexstiatus, at 2.5 metres at Clam Gardens.

After a hot breakfast we headed south again to Ribbon Reef #3. We would spend the rest of the day here.

The second dive was at Steve's Bommie. Steve's is a pinnacle similar to Lighthouse and Pixie's but is somewhat larger around. It is also a haven for marine life and some claim it is one of the best, if not the best, site for diving on the Great Barrier Reef. As usual we started at the bottom and worked our way around in a clockwise direction, ascending gradually all the way. I saw a few nudibranchs and lionfish, but did not get to see the leaf scorpionfish that were seen by others. On top of the bommie we saw the tiny true clownfish, Amphiprion percula, which has recently moved into one of the anemones. There is a family of A. percula at the base of the bommie (in 27m of water) but this was much easier to see. Despite them being popularised in the animated movie "Finding Nemo", this species, while relatively common, is rarely seen on dives on the Great Barrier Reef. (Dive details )

Two nudibranchs, Notodoris minor, at 11.5 m on Steve's Bommie.

The third dive of the day, second dive at Steve's Bommie, had someone of an aborted start. Tim and I geared up and swam on the surface to the bommie. We descended to around 14 metres when the O ring on my tank blew and I had to return to the surface. There was little we could do while in the water and so we'd have to head back to the boat. The only problem was the boat was leaving. It had broken its mooring and they were moving the boat to a safe distance from the bommie. Fortunately, Karl saw us and he and Rage came out in the tender to pick us up. Back on the boat we were able to replace the O ring and once the boat had been tied up again, we were able to start the dive again.

On the second attempt at the dive I had a really bad time with my mask. I must have got some hair in it as it was constantly leaking which was very annoying. Despite the mask troubles, we still got to see two leaf scorpionfish, , a green one and a black one, two lionfish, a very colourful nudibranch and have another go at getting photographs of the true clownfish on top of the bommie. Tim and I had a miscommunication which resulted in me heading back to the boat while he did another lap of the bommie. It was a little worrying to get out of the water without Tim behind me, especially after the difficult swim against the current. Tim showed up 5 minutes later no worse for the experience. (Dive details )

Clown anemonefish, Amphiprion percula, at 4.8 m on Steve's Bommie.

There was a night dive also at Steve's Bommie, but I bowed out as my ears were getting quite painful. I probably would have done this dive, too, if not for the aborted first attempt at the third dive of the day and the strong current.

Day 6: 1 June - Agincourt Reef

Our last day (well... half day) would be spent at Agincourt Reef. This is the closest decent diving to Port Douglas and allows us a couple of dives before heading back to Port. Most of the day boats come to Agincourt Reef.

The first dive was at Nobody's. Nobody's was a similar layout to Challenger Bay and The Cod Hole. A large sandy area with a number of large coral bommies and fingers out into the sand. Even though I didn't see anything unusual or spectacular on the dive, I still enjoyed in, especially knowing it would be my second last tropical dive in some time. (Dive details )

Diploastrea heliopora colony at 7.4 metres at Nobody's.

Our final dive was at Fish City. It is from this reef that the American divers, Eileen and Tom Lonergan, went missing in January 1998 from a day trip with "Outer Reef". Fish City is a large shallow bommie and we made one clockwise pass around the edge and then investigated the top of it. On top it had a lot of stony corals and a few large clams. (Dive details )

Last updated: 30 August 2007