How we saw Bioluminescent Plankton

We went to Koh Rong Samloem, an island near Sihanoukville, Cambodia. It took a bumpy plane flight, a bumpy minibus ride, a bumpy ferry boat, and a long walk with our backpacks on the beach (the last only because of bad directions), but we got to a nearly deserted island.


There were a few restaurants and a minimart, and few hostels/bars, but it felt really far away from it all.

Main street:


Even the dogs decided to have a beer:

We had come to see the plankton. The first night, we took the bartender/hotelier’s advice and went out at midnight. The moon had risen by then (about waning gibbous), and it was hard to see if we were actually seeing anything. A bit disappointing.

The next night though, we we out after twilight but well before moonrise (fortunately the moon rises well afterward during this moon phase), in the middle of M’Pai bay beach, with just the starlight. We were able to see the plankton very well! We moved around, figuring out how best to see the plankton, and were really amazed by it.

The plankton are all through the water around the islands but only light up from pressure. So there is nothing to see until you wade into the water and start moving around. Then, it is like being covered in pixie dust or having lit sparklers for hands. We enjoyed making them light up while keeping the water above still, and also seeing them through snorkel masks.

Unfortunately, they are so fleeting (between moving with the water currents that you need to create in order to make them light up, and that they only stay lit for 1/4th second or so) that photographing them proved impossible. Even with a wide-open aperture, the best we got was a picture with lots of high-iso noise and what was ambiguously a few lighter pixels. Some things you just have to experience.

While on the island, we also sat on the beach during the day (about the only thing to do there!).  We enjoyed watching nature all around us as there were not many people. Our favorite daytime activity was watching the many crabs.  We noted 4 different types sitting in one place on the beach, including a bigger crab. We named him “King Kong” as he was the biggest of the day.


A crab crouched down and played possum when we approached it.  It was amazing to see how well he blended in with the sand when he did this. If you did not see him before, you would have not been able to pick him out. We tried to wait him out, to see him moving again, but we couldn’t trick him into thinking we were not there. We called him “Big Daddy”. DSC06803_edited

We were truly amazed by the Sand-bubbler crab. These little guys make spheres of sand by their wholes. They make these spheres as they “clean” the sand and eat the tiny plankton/bacteria that is in the sand. The sphere is the waste product from the crab cleaning the sand.

They leave these balls all around their holes, making great sand art.


We enjoyed the sunsets from the tiny town looking over the pier. It was a hard place to get to, as it took us two days to get there and back, but the experience of the plankton was worth every bumpy ride and queasy moment. Being able to enjoy a mostly deserted island and feel as if you were swimming in a beautiful ocean alone was also a noteworthy moment for us. IMG_20170416_094307-PANODSC06867_edited

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