Underwater encounters – soft coral, skull caves and bioluminescent birdwatching

Skulls caves, waterfalls, bioluminescent birdwatching. Sometimes the most amazing diving is not the most memorable part of an adventure. A trip to Tawali Dive Resort in Papua New Guinea helped me discover one of my favourite dive sites in the world but it was everything else I found there that made this place unforgettable. Let’s dive in one last time.

Getting there

Just getting to Tawali is an adventure. First you fly from PNG’s capital Port Morseby to a remote town in PNG’s south east, called Alotau. From there a rambling mini bus drive takes you past villages and through jungle. You spot farms, villages and plane wrecks nestled in the bush. Two hours later you are unloaded at a small wooden dock. Suitcases are passed through the mini bus window and piled onto a boat. We head out as the last fishermen head in from the day on wooden canoes. A mass of green looms above a wooden jetty as dusk falls. This is Tawali, we’ve made it.

Soft corals and jungle skies

Over the coming days we left our mountainous new home to explore the nearby reefs. Motoring out on the dive boat we’d see flying fish leap out of the water and dart across the surface. One day we came upon a site called Deacon’s Reef. Looking up at the jungle I stepped off the boat and descended. Coral reef greeted me in every direction, colourful and alive with a rainbow of fish. Swimming along I followed our guide, so far nothing unusual here. We weaved between rocks covered in sponges and encrusting coral. I found myself in a gully, a rock wall on one side rose from the sea floor to the surface.

Looking up took my breath away. It wasn’t a wall it was the edge of the land. Above me the sunlight shimmered through the jungle, creating a sparkling green ceiling. The gully grew shallower, I was swimming upwards towards the jungle. Looking away from the land I saw a mass of vibrant colours. Soft corals in the most delicate shades of pink, yellow and orange grew in clumps. I floated at the bottom of the gully. Looking up at the soft corals, fish swam above me like birds among the reflections of the jungle. It was a disorienting, beautiful world.

Soft corals don’t grow calcium carbonate skeletons, they’re not reef builders like hard corals. Every soft coral polyp has eight tentacles instead of six, placing soft corals and sea fans in in a group called Octocorals. Some octocorals have algae in their tissues called zooxanthellae. This algae converts sunlight into food through photosynthesis, similar to terrestrial plants. Other soft corals don’t contain any zooxanthellae. They rely on underwater currents to bring their plankton food to them. These algae-free soft corals are easy to spot as they are bright shades of red, orange, pink and purple.

Surfacing from the dive, the surreal feeling persisted as we went on a shopping trip in the ocean. Local villagers had paddled out in their canoes to sell jewellery and shells. Mitch picked a necklace for me while bobbing beside the canoe.

Waterfalls and skull caves

Back at the resort that afternoon we kept exploring. A local guide, Gilbert, took us to see some caves. It was overcast but muggy in the jungle, the air felt heavy with water. Descending into the first cave we felt the temperature drop. Cool relief! As our eyes adjusted to the darkness, we followed a short path deeper, down into the earth. Rounding a bend, we came upon a strange formation.

White stalactites hung from the cave ceiling. When the torch beam hit them, they sparkled as if covered in glitter. My eyes slid down to a pile of white rocks stacked up at their base. But they weren’t rocks. They were skulls. Piles and piles of human skulls filled the cave. Empty eye sockets stared blankly up at us. Some skulls had begun crystallising and also glittered. It was eerie, but beautiful. A natural tribute to ancestors. Or a hiding place of murdered enemies? Like everything in PNG you can never be quite sure.

Back in the daylight and the heat we ventured on. The sun had begun to go down and the dusk was creeping in. Following a path through the jungle we arrived at a waterfall. The forest was quiet except for the splash of water. A calming end to an action filled day. We were all silent on the boat back to the resort.

Bioluminescent bird watching

For our last day on the island we set our alarms for 3am. We were going bird watching. By 4am we were on a boat heading into the dark sea. Stars twinkled above, fading as the dawn approached. It was pitch black except for a strange light trailing the boat. Water splashing along the boat and in our wake flashed blue, like electric sparks in the black ocean. The neon blue light spread along the sides as we sped up. Bioluminescence.

Many marine organisms can produce light from a chemical reaction within their bodies. This is called bioluminescence. They do this when being attacked, trying to attract a mate or when physically disturbed, such as when a boat makes waves. Lots of animals can produce bioluminescence, including plankton, jellyfish, sea stars, fish and sharks. The one thing these species all contain is a molecule called luciferin that creates light when it reacts with oxygen.

In the predawn light we began scrambling uphill. The muddy path wound up the side of a mountain. Bugs landed on us, the mud sucked at out sandals. Our guide sped ahead, nimble in his thongs, hacking errant branches off the path with his bush knife. We trekked onwards, upwards, the day grew lighter. Finally we stopped in a small clearing at the top. Our guide looked up. We did too, not quite sure what to look for.

Finally, he pointed up. I couldn’t see anything. I stared at the green, hoping a shape would materialise. He pulled me closer and pointed again with his arm next to my head. There it was, a brown, bedraggled shape amongst the leaves. A bird of paradise. It had arrived at its morning roost to sing its mating call. But today it was silent. We all looked up, waiting. But he flew from one tree to another then left in silence to get on with his day. It was an incredible end to our trip. We headed back to the island to pack and say our goodbyes. A week of underwater and topside encounters had left us with a lifetime of memories and a vow to return.

This was the final post in the Underwater Encounters series! I hope you’ve enjoyed reading about some of my favourite marine memories and this has inspired you to get out and make your own. This series was produced as part of an assignment for my Masters in Science Communication. If you have any tips, tricks or other feedback to help me improve my science communication please comment or message me. It’s time for me to abandon ship. Until next time may you have fair winds and calm seas.

Underwater encounters – dancing sharks and moody fish

For the second post in this series I interviewed a special guest. Let me introduce Paul Baskys, a dive instructor who lived and dived in Papua New Guinea for three years. I sat down with Paul and asked about his most memorable underwater encounters. Here’s what he told me…

Titan Triggerfish

Paul’s first story takes us to the Pai 2, a wreck dive south east of Port Moresby, PNG. This old Japanese fishing boat was purposely sunk in 1982 to form an artificial reef dive site. It’s a great dive, you slowly swim around the boat, which is bursting with life. Schools of glassfish smother the wreck. Colourful sponges and soft corals decorate the rusted steel hull.

While Paul was exploring Pai 2 his dive buddy swam up to him and began gesturing. In strange underwater sign language his buddy, Mitch, pointed at the stern then crossed his arms in a big X shape. Paul nodded, don’t go near the stern, got it! He looked over but couldn’t see what Mitch was so worried about and continued exploring the wreck.

Everyone was running low on air so it was time to head back to the boat. Paul swum back over the wreck, past the stern, heading towards the reef where the boat was waiting. Something caught his eye. A titan triggerfish! These large fish have a sharp beak for crunching through coral and sea urchins. Their eyes are enormous and independently rotate to follow your every move. They’re one of Paul’s favourite species and he hadn’t seen them on the Pai 2 before.

The triggerfish looked like it was feeding. Its snout nudged around in the algae growing on the wreck. Paul swam closer to shoot some video. The fish tensed its body like an athlete at the start of a 100 metre sprint. It turned away, then suddenly spun and swam straight at Paul. He quickly retreated. The triggerfish snapped at the camera, spun around, and lunged at the camera again. Satisfied the human was far enough away the triggerfish went back to its business.

Paul finally understood what Mitch was warning him about. Mitch had seen the nest of triggerfish eggs, a pink gelatinous mass, early in the dive. Both male and female triggerfish will aggressively defend their nests. On a dive a few months later Paul saw a nesting triggerfish under a boat mooring. Having learnt his lesson, he was able to steer a group of divers away from a similar attack.

Grey Reef Shark

The second story also took place in PNG when Paul was leading a dive off Fishermen’s Island (aka Daugo Island in the local language). The dive is on a coral wall near the edge of the continental shelf, where the ocean floor drops down to 600 metres. Divers jump in and drift along the wall, meeting the boat at a rendezvous point.

Looking away from the wall Paul spotted a shark. It was an adult grey reef shark, about two metres long. Normally sharks propel themselves forward using their tail (caudal fin) which makes their head slowly wiggle from left to right. This shark’s movements were exaggerated. It was bending its head almost 90 degrees to each side. Paul looked back at the divers obliviously staring at the wall and decided to keep an eye on shark that was still about 40 metres away.

The divers continued to drift along the wall. The shark arched its back and dropped its front (pectoral) fins. Paul decided it was time to move the divers on. He got the group’s attention and signalled it was time to head to the rendezvous point. One diver got excited, waving at everyone, and pointing behind Paul. All nine divers swam past Paul straight towards the shark. This was bad as dive leader it would be his fault if something happened, but also good because there were now nine other people between him and the shark.

The shark continued its threat display and swam closer. It was now 15 metres away. Paul herded the group back towards the boat. Out of the water everyone was excited about the shark encounter. One diver remarked, “Wasn’t that an awesome dance the shark was doing?!”. Paul dived the site again over the coming months and saw many grey reef sharks but luckily none were ‘dancing’.

Paul’s stories highlight the incredible natural behaviours we can witness up close underwater. These stories also serve as a warning to learn a little about the creatures you may encounter so you know what they’re really trying to tell you.

To read more about shark threat displays check out R. Aiden Martin’s article https://www.tandfonline.com/doi/full/10.1080/10236240601154872