THE EXPEDITION

EXPERIENCE REQUIRED - ADVANCED OPEN WATER LEVEL WITH 50 DIVES MIN

This is one of the most intense and dynamic spawning expeditions we offer—combining two completely different natural events into one perfectly timed adventure.

Only twice a year—June and July—the lunar cycles align to make this possible. Miss these windows, and the opportunity is gone.

Choose between a land-based expedition or go all-in with a liveaboard experience, with a schedule built around early morning dives and late-night action—putting you in the water when both spectacles are at their peak.

We begin with the raw power of the Bumphead Parrotfish spawning event.

At first light, you’ll witness what is widely considered the largest aggregation of bumphead parrotfish on the planet—hundreds to over a thousand massive fish gathering, stacking, and surging forward in a slow-building wave of energy before erupting into spawning. It’s heavy, deliberate, and primal—an unforgettable start to the day.

Then, as the sun sets, the mood shifts completely.

We return to the water under fading light for the Camouflage Grouper spawning.

From their hiding places within the reef, hundreds of groupers begin to emerge—rising into the water column as males aggressively chase females in a fast-paced, chaotic display. The energy builds rapidly, and as spawning begins, the scene becomes charged with tension.

Because they’re not alone.

Grey reef sharks and lemon sharks move in, drawn by the opportunity, circling and darting through the aggregation—turning the entire event into a high-stakes encounter where predator and prey collide in real time.

Two completely different worlds.
One perfectly timed expedition.

To experience the largest bumphead aggregation on Earth by sunrise… and a predator-charged grouper spawning by night… is something very few divers will ever witness in a single trip.

Once the spawning events have passed, we continue exploring the very best of Palau—diving manta ray cleaning stations, shark-filled channels, dramatic caverns, blue holes, swim-throughs, and even the surreal waters of Jellyfish Lake.

Sunrise power. Night-time chaos. Perfect timing.

This isn’t just diving—it’s front-row access to nature at its most raw and unfiltered.

PALAU

Palau is widely regarded as one of the finest dive destinations on the planet—and for good reason. Its reefs are shaped by dramatic underwater topography, including sheer drop-offs, blue holes, caverns, caves, and fast-moving channels. Visibility is often exceptional, regularly reaching up to 100ft (30m), giving you that true “endless blue” feeling.

Wreck dives closer to Koror offer a different atmosphere, where visibility is typically reduced to around 15–45ft (5–15m)—but what they lack in clarity, they more than make up for in history and character.

Palau can be dived year-round, though the wetter season generally runs from July through October. Water temperatures are consistently warm, ranging between 81–86°F (27–30°C), making a 3mm wetsuit ideal for most conditions. That said, Palau likes to keep things interesting—seasonal thermoclines can drop temperatures into the mid-60s°F (23–26°C), especially on deeper dives.

Most sites are accessed via 45–60 minute speedboat rides from Koror, with the prime diving areas located around Ngemelis Islands and Peleliu—home to some of the most iconic dives in Micronesia. For this reason we choose a liveaboard experience to maximise our time on the ocean, offering four dives a day with early starts and late sunset dives.

Currents are a defining feature of diving in Palau. Driven by the Pacific Ocean, they create the conditions that make this destination so spectacular—but they also demand respect. Many sites are best suited for experienced divers, and a reef hook is essential, particularly on the outer reef walls like the legendary Blue Corner, where you’ll hook in and watch the ocean unfold in front of you.

For those with a passion for history, Palau also delivers. The waters around Koror are scattered with World War II wrecks, from cargo ships and transport vessels to navy destroyers and even Japanese Zero aircraft. Many are remarkably intact and easily accessible, offering a completely different—but equally compelling—side of Palau diving.

CAMOUFLAGE GROUPERS

In the days leading up to the new moon, Palau’s channels begin to stir. From deep within the reef, hundreds of Camouflage Groupers (Epinephelus polyphekadion) gather, slowly building in number as they prepare for one of the ocean’s most intense nocturnal spawning events.

We begin our expedition ahead of the new moon, diving Palau’s iconic current-swept sites as the anticipation builds. But as the sun drops below the horizon, everything changes.

This is where the real action begins.

Under the cover of darkness, we enter the water. As night falls, the reef transforms—quiet at first, almost still—until movement begins to emerge from the shadows.

From their hiding places, the groupers rise.

What starts as scattered individuals quickly becomes a dense, fast-moving aggregation, with males aggressively pursuing females in a chaotic, high-energy display. The pace builds rapidly, and then—suddenly—the entire group surges into the water column, releasing clouds of eggs and milt in a synchronized burst.

It’s fast. It’s unpredictable. It’s electric.

An underwater firework display unfolding in the darkness.

And just when you think it couldn’t get any more intense… the predators arrive.

Grey reef sharks and large lemon sharks move in, circling the aggregation, darting through the chaos—drawn by the sheer density of life and opportunity. The result is a raw, high-stakes encounter where instinct, survival, and timing collide.

This isn’t just a dive……………This is the ocean at its most unforgiving—and most spectacular.

Miss the night… and you miss everything.

BUMPHEAD PARROTFISH

In the days leading up to the new moon, something remarkable begins to take shape across Palau’s outer reefs and channels. From the lagoon and surrounding reef systems, hundreds—often thousands—of Bumphead Parrotfish (Bolbometopon muricatum) begin to gather, slowly building in numbers as they prepare for one of the ocean’s most extraordinary spawning events.

We start our expedition ahead of the new moon, diving Palau’s iconic current-swept sites as the anticipation builds. With each passing day, the signs become clearer—the fish are arriving, the energy is shifting, and the stage is being set.

Then comes the moment.

Before sunrise, we head out. As the first light breaks over the horizon, we descend into position and wait.

Out of the blue, they appear.

A steady procession of massive bumpheads begins to pour out of the lagoon, flowing onto the reef like a living river—building, layer by layer, into a powerful aggregation. What starts as a slow, deliberate movement quickly transforms into a surge of energy, as the entire group pushes forward to spawn, releasing clouds of life into the water column.

It’s not chaotic like other spawning events—it’s something different.

There’s a rhythm to it. A flow. A raw, majestic choreography that feels almost unreal to witness.

This is one of nature’s true spectacles—quietly powerful, deeply primal, and unforgettable.

Miss it… and you’d never know it happened………Be there… and it stays with you forever.

PALAU SIREN - LIVEABOARD

LIVEABOARD

ALL LIVE-ABOARD RATES ARE BASED ON PER PERSON.

ALL DATES

NEW MOON GROUPER & BUMPHEAD COMBO EXPEDITIONS

PALAU SIREN LIVEABOARD

2027 AVAILABLE DATES

2028 AVAILABLE DATES

2029 AVAILABLE DATES

PALAU LOCATION

PALAU SIREN ITINERARY

PRICE BREAKDOWN

EXCLUDES

• International & Domestic Flight

• Park Permits

• Gratuities

• Rental and Dive Gears

DIVE INFORMATION

WATER TEMPERATURE - 27c / 85F

WETSUIT - 3mm / 5mm

• Blue Corner, one of Palau's most magical dives, is known for its sheer abundance of underwater life and reef configuration – the corner sticks out into the open ocean and then drops to the depths. Divers are dazzled by the incredible variety of fish, including barracudas, jacks, Napoleon wrasses and schooling grey reef sharks. Strong tidal currents render it a dive for the more experienced – a reef hook is a must to remain stationary in the current.

• Blue Holes, may well be Palau's most scenic dive. It features four vertical shafts that open on the top of the reef and descend to a large cavern that exits on the outer wall at about 25m. Drifting down the shafts is a delight, especially when the sun is high. Dancing rays of sunlight flood through these openings and play with the blue hues. Schools of fish patrol the huge bottom exit, with dark blue ambient light as a background.

• German Channel, Given the right set of circumstances, a dive at German Channel can be an unforgettable experience. Manta rays regularly visit this channel, which was blasted by the Germans to ease boat passage during their 1899 to 1914 Palau occupation. The mouth of the channel features some nice sandy areas with small cleaning stations, where mantas (usually two to five individuals) come to have parasites removed by little cleaner wrasses in less than 20m of water.

• Peleliu Island, If you'd like to temporarily escape the relative hustle and bustle of the capital, the small coral island of Peleliu, in the south of the archipelago, offers a tranquil option. There's only one village – Klouklubed – and often it will seem like you've got the entire island all to yourself. The diving here is concentrated around the south East tip of the Island. Deep walls, strong currents and an abundance of fish life make this one of Palaus best dive locations.

• Ulong Channel, is one of most thrilling dives in Palau. Divers start at the mouth of the channel, which consistently sizzles with fish action. Divers usually hook themselves to the reef to see hunting grey and whitetip sharks, jacks, barracudas and groupers, before drifting with the current along the channel. The seascape is incredibly scenic: the sea floor is carved by large parallel-running white-sand valleys, bounded by healthy coral formations and dotted with massive sections of sprawling lettuce corals.

• Siaes Corner, When the tide is running and the month is right you can see more than 300 grey reef sharks here. Siaes Corner is a current-swept point that plunges vertically to about 50m. After jumping in the water, divers drift along the wall to the corner. As you reach the corner, you attach your hook to a dead coral to watch for electric fish action, which usually includes grey sharks, blackbar barracudas, jacks, bumphead parrotfish, anthias and fusiliers.

• Shark City, is the outer most promentory in Ulong and sometimes one of the best dives in Palau. Conditions are similar to Peleliu with strong current and action dives along with high rewards such as bull sharks, oceanic blacktips and pelagic encounters. The corals and reef life is also spectacular.

SPAWNING DIVE INFORMATION

LATE NIGHT DIVES

POTENTIAL CURRENT DIVES

The yearly aggregation of camouflage grouper (Epinephelus polyphekadion) has been known for many decades in Palau. Scientists have come and gone since the late 70’s observing their patterns and protecting them and their vulnerable spawning sites around the islands during the months of June through to August. Since then no-one had witnessed or at least not documented any spawning style, timing or pattern in Palau until 2015 when Unique Dive Expeditions crew slowly put all the pieces of the puzzle together.

over the last six years spent large periods of time watching and observing the camouflage grouper fighting for territory, displaying sexual dimorphism (color change) but we had not witnessed spawning and neither had anyone else in Palau. We wanted to put that final piece of the puzzle to rest and so sat painfully at times watching and waiting each year passing by as their short window came and went.As the fish only stayed at the site for a limited period of time, each year we would slowly tick off all the possible combinations of tide, moon and time until one day it all fitted together. We were not honestly expecting the camouflaged grouper (Epinephelus polyphekadion) spawning to be such a spectacle. Our other spawning expeditions of snappers (Lutjanus bohar) and bumphead parrotfish (Bolbometepon muricatum) had close to guarantee bullsharks (Carcharhinus leucas) and oceanic blacktip sharks (Carcharhinus limbatus) during spawning time and that we thought was going to be hard to beat. 

During the daytime we only saw a handful of sharks around this aggregation. A few whitetip reef sharks  (Triaenodon obesus) and grey reef sharks (Carcharhinus amblyrhynchos) here and there but nothing to make you really excited and so our expectation levels were low on shark predation.As night fell everything was about to change, large sickle-fin lemon sharks (Negaprion acutidens), which I had only seen a handful of times in Palau begin to appear. These quite large, agile for their size shark, seek out the grouper using their sensors at night. Any fish that moves is a target so the groupers only defense is by lying completely still under the corals. As the spawning time approaches more species of sharks begin to appear, grey reefs (Carcharhinus amblyrhynchos) and oceanic blacktip sharks (Carcharhinus limbatus) lurk through the night.

.As the spawning erupts our patient waiting is over and some of the questions we have been wondering our answered. Males push out their females that they have been protecting from their night time holes for several days, both rising to the surface spiraling like a mini tornado as they release their gametes.Oceanic blacktips (Carcharhinus limbatus) and grey reefs (Carcharhinus amblyrhynchos) buzz through your lights trying to pick off the grouper as they spawn in front of you, their silhouettes lit up by our lights. The expedition we thought might not be so interesting turned out to be our most fascinating.

PRESENTATIONS

During your stay with us your Expedition Leader and Location Expert will be working together delivering you in depth presentations regarding the biology of what we are witnessing. These presentations have taken years to formulate and develop and what makes part of our collaboration with Unique Dive Expeditions so special.

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