Join Unique Ocean Expeditions for one of the most powerful and rarely witnessed underwater events on the planet, where the ocean doesn’t just come alive—it erupts with raw, untamed energy.
Each month, in the days leading up to the new moon, thousands of Bumphead Parrotfish (Bolbometopon muricatum) gather at specific channels to spawn.
What begins as small groups builds rapidly into a dense, slow-moving mass of giants—fish weighing over 40kg—cruising against the current as the tension builds toward the main event.
This is not chance; this is precision.
After years of exploration, hundreds of dives, and a deep understanding of moon phase, tide, and current flow, we’ve fine-tuned these expeditions to place you in the water at the exact moment when everything aligns.
We focus on one primary site—widely regarded as the largest aggregation of Bumphead Parrotfish on Earth. As the first light breaks on the horizon, we descend into position.
Then it begins.
From the blue, the school appears—hundreds… then nearly a thousand—stacking up in front of you. The energy builds slowly, almost eerily calm at first… before suddenly exploding into motion. The entire aggregation surges forward, bodies colliding, tails beating, releasing clouds of eggs and milt into the water column in a chaotic, synchronized rush.
You don’t just watch it; you feel it.
This is nature at its most primal—raw power, scale, and intensity that very few divers will ever experience.
Over the course of the expedition, you’ll:
Dive the primary aggregation site at the peak of the new moon cycle
Experience multiple spawning dives in high-energy conditions
Explore Palau’s world-class reefs, blue holes, corners, and iconic drift dives
Gain real understanding through daily briefings and in-depth presentations
Expect early mornings, strong currents, and serious diving—this is for those who want more than just beautiful reefs.
All of our unique Palau itineraries are hosted by Palau Siren Liveaboard. With a liveaboard diving experience, you maximize your time on the best sites when conditions are right.
Massive fish. Explosive action. Perfect timing.
This is Palau at its wildest. Miss the moon, and you miss the moment.
Our Palau expeditions are designed for passionate divers who want to experience some of the most spectacular natural events in the ocean.
You do not need to be a technical diver, a professional photographer, or someone with hundreds of dives — but you do need to be a confident diver.
We require a minimum of 50 logged dives and a PADI Advanced Open Water certification (or equivalent). Guests should also have previous experience diving in currents, as many of Palau’s most exciting encounters happen where ocean movement brings marine life together.
Palau is famous for its drift diving, reef hooks, spawning aggregations, and fast-changing conditions. Our guides are there to position the group safely and at the right moment, but divers should already be comfortable controlling their buoyancy, descending without difficulty, and diving as part of a group in open ocean environments.
For specialty experiences such as bumphead parrotfish spawning dives, camouflage grouper night spawning dives, and blackwater dives (when offered), previous night diving experience is required. These are some of the most unique wildlife encounters on the planet, but they require confidence in low-light conditions, good awareness, and precise buoyancy control.
You do not need thousands of dives. You just need solid experience, good dive skills, and a sense of adventure.
The 40m S/Y Palau Siren was designed by divers for divers to provide superior ease and comfort.
Aboard Palau Siren, scuba enthusiasts will explore pristine, remote dive sites and enjoy lavish accommodations.
The Palau Siren crew of 12 is on hand to ensure guest satisfaction for up to 16 divers.
This intimate liveaboard offers ample space including 8 large cabins equipped with individual climate control, entertainment system and en suite bathrooms.
The SY Palau Siren also features an air-conditioned lounge with cocktail bar, sofas, 42 inch flat screen and movie network.
Massage service is available daily. The decks feature a covered outdoor dining area where meals and refreshments will be served buffet style throughout the day and an upper level sun deck with cushioned loungers.
A large shaded diving deck provides individual stations and personal storage lockers.
Guests are also provided with tanks, weights, BCD, regulator, 3mm wetsuit, mask and fins free of charge.
The main lounge offers a fully equipped camera and video station of professional quality.
Palau Siren schedules year round dive trips offering scuba divers the thrill of deep dives, the tranquility of drift dives and the opportunity to encounter huge numbers of pelagic.
Book now to dive the spectacular Palau waters on a Palau Siren liveaboard diving holiday.Large air-conditioned cabins each with their own personal audio-visual entertainment system and ensuite bathrooms with hot water.
All rooms are lavished with luxury extra's including bathrobes, hair dryers, towels, individually controlled mood lighting and individual controls for your air-conditioning unit
Deluxe Twin Cabins – B3, B5, B6 & B7 / B4
The Deluxe Twin Cabins on the Palau Siren are thoughtfully designed to combine comfort and functionality.
Cabins B3, B5, and B7 offer flexible twin or double-sharing arrangements, while B4 features cozy bunk beds for twin sharing.
Each cabin provides ample living space, smart storage solutions, and a relaxing atmosphere, ensuring two guests can enjoy both privacy and convenience during their underwater adventures.
Modern amenities and a serene design make these cabins a perfect retreat after a day of diving in Palau’s stunning waters.
Deluxe Double Cabins – B1 & B2
The Deluxe Double Cabins on the Palau Siren feature a comfortable queen-sized bed, providing a perfect space for two guests to relax after a day of diving.
Thoughtfully designed with both comfort and practicality in mind, each cabin offers generous living space, smart storage solutions, and a serene ambiance.
These cabins combine cozy elegance with functionality, ensuring that every guest enjoys a restful and convenient retreat in the heart of Palau’s breathtaking waters.
Sam’s Tours, Koror at 17:00
Disembarkation: Sam’s Tours, Koror at 10:00
Transfer to Sam's Tours from Koror Airport* or a local hotel is provided free of charge on embarkation day. Pick-up time from local hotels is usually between 16:30 and 17:00.
*Airport pick-up is dependent on flight arrival time. Guests arriving in the early hours of the morning on embarkation day need to arrange hotel accommodation.
Transfer from Sam's Tours to local hotels or Koror Airport is provided free of charge upon disembarkation at 10:00 only.
Guests with evening or night flight departures who have made arrangements for day use at local hotels will be transferred from Sam's Tours to the hotel but are responsible for arranging their transfers from the hotel to the airport.
Likewise, guests who wish to leave their luggage at Sam's Tours and explore downtown Koror before their departure are also responsible for
arranging their own transport to the airport.
Marine Park Fees, drills and all safety procedures are carried out on Day 1
Palau Islands permits and fees: (payable onboard only)
7 nights: 230 USD per person
10 nights: 300 USD per person
These fees are mandatory and subject to change without notice. The applicable amount at the
time of your liveaboard departure will be added to your onboard bill to be paid before disembarkation.
The Ngemelis Island area is home to some of Palau’s most legendary dive sites and represents everything that makes this destination world-famous — dramatic walls, powerful currents, huge schools of fish, healthy coral reefs, and encounters with some of the Pacific’s most iconic marine life.
This is where we find sites such as Blue Corner, Blue Holes, New Drop Off, Big Drop Off, and German Channel. Each site offers something completely different — from hooking in at Blue Corner watching grey reef sharks cruise effortlessly in the current, to descending through the cathedral-like shafts of Blue Holes, or exploring vertical walls covered in sea fans, soft corals, and marine life.
German Channel is one of Palau’s most exciting cleaning stations, where manta rays can appear from the blue and circle gracefully above the reef. Large schools of barracuda, jacks, snapper, turtles, Napoleon wrasse, and reef sharks are regular encounters throughout this area, making every dive unpredictable and full of possibilities.
The Ngemelis reefs are a perfect example of why Palau remains one of the world’s greatest dive destinations. Here, every dive is shaped by the ocean — the tides, currents, and seasons deciding what we may encounter. No two dives are ever the same, and that is exactly what makes this area so special.
Day 4: Departure from Ulong Island Area after lunch followed by a sunset dive on arrival to Ngemelis Island anchorage area.
The following days, your Cruise Director will schedule up to 4 dives per day; 3 day dives and either a sunset or a night dive.
A typical diving day is scheduled as follows:
● 6.30am - Light Breakfast followed by a briefing & Dive 1
● 9.30am - Full Breakfast, relaxation followed by briefing & Dive 2
● 12.00pm - Lunch, relaxation followed by briefing & Dive 3
● 4.00pm - Snack
● 6.00pm - Briefing for Sunset or Night dive
● 7.30pm Dinner
Located at the southern end of Palau’s reef system, Peleliu offers some of the most exciting and adventurous diving in Micronesia. Exposed to the open Pacific Ocean, these reefs are known for dramatic walls, strong currents, incredible visibility, and encounters with larger marine life.
Peleliu has a different feeling from many of Palau’s other dive areas — it feels wilder, more remote, and less frequently visited. The currents that sweep around the island bring nutrient-rich water from the deep ocean, creating the perfect conditions for healthy reefs and attracting a wide variety of marine life.
Dive sites such as Peleliu Corner, Peleliu Express, Orange Beach, and Peleliu Wall offer thrilling drift dives, beautiful coral formations, schooling fish, reef sharks, turtles, and the chance of unexpected encounters from the blue. When conditions align, Peleliu can deliver some of the most exciting dives Palau has to offer.
But Peleliu is not only famous underwater.
The island was also the location of one of the fiercest battles of the Pacific during World War II. In 1944, American and Japanese forces fought here in the Battle of Peleliu, leaving behind a landscape filled with history. Today, many reminders remain, including tanks, aircraft wreckage, bunkers, caves, and battlefield sites hidden throughout the island.
During our visit, guests have the option to replace one dive with a guided land tour of Peleliu. This powerful experience explores the history of the island and provides a deeper understanding of the events that took place here more than 80 years ago.
Whether exploring the reefs below or walking through history above, Peleliu remains one of Palau’s most unforgettable destinations.
After Breakfast we leave the Palau Siren by private speedboat and travel south to Peleliu...
A typical diving day is scheduled as follows:
● 6.30am - Breakfast followed by a briefing & Dive 1
● 9.30am - Full Breakfast, relaxation followed by briefing & Dive 2
● 12.00pm - Lunch, relaxation followed by briefing & Dive 3
● 4.00pm - Snack
● 6.00pm - Briefing for Sunset or Night dive
● 7.30pm Dinner
The Ulong area is one of Palau’s most diverse regions, offering a completely different experience from the famous walls of the outer reef. Here we explore a combination of channels, coral gardens, historical sites, and current-driven dives where Palau’s marine life is at its very best.
Ulong Channel is one of Palau’s signature dives — a beautiful drift through a natural underwater corridor lined with some of the healthiest hard coral formations in Micronesia. When the currents are moving, grey reef sharks patrol the entrance, schools of jacks and barracuda gather in the blue, and divers finish by flying effortlessly through the channel past huge lettuce coral formations.
The area is also home to sites such as Siaes Corner, Siaes Tunnel, and Shark City, offering dramatic walls, caverns, shark action, schooling fish, and incredible wide-angle photography opportunities. Every dive here is dictated by the tides, and when conditions align, Ulong delivers some of Palau’s most exciting underwater encounters.
Later in the expedition we return to this special area for one of Palau’s greatest natural events — the Bumphead Parrotfish spawning aggregation. Before sunrise, hundreds of these prehistoric-looking fish gather together, following ancient rhythms controlled by the moon and tides. Witnessing this behavior is one of the true highlights of diving Palau and exactly the kind of rare ocean event our expeditions are designed around.
Day 2: Departure from Malakal Harbour after breakfast followed by a check dive, and up to 3
subsequent dives, as outlined below.
Your Cruise Director will schedule up to 4 dives per day; 3 day dives and either a sunset or a night dive. A typical diving day is scheduled as follows:
● 6.30am - Light Breakfast followed by a briefing & Dive 1
● 9.30am - Full Breakfast, relaxation followed by briefing & Dive 2
● 12.00pm - Lunch, relaxation followed by briefing & Dive 3
● 4.00pm - Snack
● 6.00pm - Briefing for Sunset or Night dive
● 7.30pm Dinner
As our expedition enters its final days, we return to the Ulong area — but this time with a very different focus. Earlier in the trip we explored Ulong’s famous channels, walls, and reefs; now we come back as the moon phase and tides align for some of Palau’s most extraordinary natural events.
Our main focus is the Bumphead Parrotfish spawning aggregation, one of the most unique wildlife encounters in the ocean. Before sunrise, hundreds of these prehistoric-looking fish gather together in the shallow reefs, following ancient rhythms controlled by the moon and tides. Watching the build-up, courtship behavior, and explosive spawning event is a rare experience that very few divers ever witness.
During this period, we also have additional opportunities to revisit Shark City, where the Blue-Lined Sea Bream aggregation may still be active. These huge gatherings of fish create incredible scenes as the reef comes alive with movement, energy, and predator activity.
As the expedition comes to a close, we continue exploring the best conditions Ulong has to offer, from exciting drift dives through Ulong Channel to special night dives where we search for nocturnal marine life, including several species of spawning groupers. It is the perfect way to finish our journey — letting the moon, tides, and ocean decide the final surprises.
Day 8: We shall finish our expedition diving two days back at Ulong Island area for the Bumphead Parrotfish Spawning subsequent dives, as outlined below.
Your Cruise Director will schedule up to 4 dives per day; 3 day dives and either a sunset or a night dive. A typical diving day is scheduled as follows:
● 5.30am - Light Breakfast followed by a briefing & Dive 1
● 8.30am - Full Breakfast, relaxation followed by briefing & Dive 2
● 12.00pm - Lunch, relaxation followed by briefing & Dive 3
● 4.00pm - Snack
● 6.00pm - Briefing for Sunset or Night dive
● 7.30pm Dinner
Day before disembarkation:
For your last full day on board, we schedule up to 3 dives* before the boat cruises back to
Malakal Harbour, where it will remain at anchor overnight.
Disembarkation day: Following breakfast on board, disembarkation is scheduled for 10:00.
*We kindly request that guests check their flight departure times to ensure they leave a
minimum of 24 hours between their final dive and their flight home.
Fishing is NOT permitted on Palau Siren, under any circumstances.
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 nearly a thousand 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.
Richard Barnden is the founder of Unique Ocean Expeditions, a specialist scuba diving travel company created to bring divers closer to some of the ocean’s most extraordinary natural events. An award-winning underwater photographer, Richard has spent nearly two decades exploring, guiding, and documenting marine life throughout the Pacific Ocean.
After more than 20 years working in the waters of Palau, Richard developed a deep understanding of the timing, locations, and conditions needed to witness some of nature’s rarest underwater encounters. His work focuses on predictable marine events shaped by moon phases, tides, and seasonal behavior — including fish spawning aggregations and blackwater night diving.
Through years of observation and photography, Richard has documented events that few divers ever experience, from mass spawning aggregations involving thousands of fish to the mysterious larval stages of marine life found during blackwater dives.
Unique Ocean Expeditions was created to share these moments with small groups of passionate divers — combining experience, patience, and timing to be in the right place, at the right time.
Richard moved to Palau in his early twenties as a video pro and later became the cruise director of multiple live-aboards where he continued his passion of filming. After building a large collection of data and photos of spawning aggregations which at the time he knew very little about he went on to spend the next decade trying to understand their predictabilities.
Richard now organises multiple spawning expeditions in Palau each year, these spawning expeditions are tailored around lunar phases to observe fish reproduction mainly during the early hours of the morning. By night Richard spends most of his time with his guests photographing plankton and their environments, a relatively new kind of night dive called blackwater diving.
His long-term research has played a key role in unlocking some of the spawning patterns of species such as the camouflage grouper and Lutjanus bohar. As a photographer, he is well known for capturing these fleeting, high-energy moments—from explosive spawning events to the surreal, otherworldly creatures encountered during blackwater dives.
Combining deep field knowledge with a relentless pursuit of the extraordinary, Richard continues to push the boundaries of exploratory diving—bringing his guests face-to-face with some of the ocean’s most spectacular and least-understood phenomena.
RICHARD BARNDEN EXPEDITION LEADER
UNIQUE OCEAN EXPEDITIONS creates Worldwide scuba diving expeditions timed with nature, guided by experience, and created for those seeking the ocean’s rarest encounters.
