Ulong Channel

“Always be yourself. Unless you can be a mermaid. Then always be a mermaid.”

- Slogan of the online network Girls that Scuba, whose members refer to each other as mermaids

One of the great things about SCUBA diving for me as a marine biologist is the chance to experience the environments I study in person. It’s one thing to read a textbook about how sunlight attenuates in water, how the temperature drops below the thermocline, how currents are steered by the bathymetry of the seafloor. It’s a completely different proposition to strap on a SCUBA tank, become an underwater creature, and go visit the reef yourself. You’ll notice that everything begins to look blue-green as you descend. You’ll feel like your head has been dunked in ice water as you cross the thermocline. You’ll feel the current push you along, following the contours of the rock below.

Friends, today, I experienced the environment in person as Carl and I dove in Ulong Channel. Our dive started with a gentle swim along a coral reef. Like most of the reefs in Palau, it was a vertical wall, and we could feel the incoming tidal current pushing us upward onto the plateau. Eventually, our guide signaled for us to ascend to the plateau and anchor in with our reef hooks. A reef hook is exactly what it sounds like - a strong metallic hook with a thick, woven line and a clip at the other end. You find a solid piece of dead coral, secure the hook, stretch out the line, and clip the other end to your gear. You inflate your buoyancy compensator slightly and float above the reef at anchor. It’s like being a human balloon.

We hooked into the reef and waited for about 20 minutes. The whole time, gray reef sharks swam back and forth in front of us, and schools of silver fish flickered past. The current grew stronger, too. We waited until the current was strongest during the incoming tide. To be honest, I was beginning to wonder if my reef hook would hold me as the force of the water stretched my line to its limit and vibrated my gear. Just then, the guide signaled to release our hooks, and we drifted with the current through Ulong Channel.

It felt like I was flying. The current carried me along, and I passed over coral after coral in the channel. The flow was too strong to swim against and extremely difficult to swim across (I tried once), but I was able to steer with my fins. For another half hour, we drifted with the current through the channel. The seafloor was covered with stony corals, rigid living rocks that can withstand the sheer force of the water rushing through the channel 4 times each day. I thought about the larvae carried on the current to the rocky habitat, about the plankton delivered to the corals' hungry tentacles at night. I dropped down to a sandy patch and felt the velocity slow in the benthic boundary layer. I passed over a large coral mound and felt the higher speed near the summit. The guide lead us through a narrow passage, and I could feel the flow become more turbulent in the complex space. It was an absolutely amazing dive.

Ulong Channel is one of my favorite dive sites in Palau. It offered a unique chance to feel the current and experience the environmental factors affecting the coral reef in person. I was grateful for the chance to dive it!