Sunken Island
An isolated pinnacle 10 km off Moalboal, its 12 m summit at 23 to 25 m reached hand over hand down a mooring line through open blue.
Last updated August 2026
The dive
Nothing is visible from the boat. A mooring buoy sits in open water with Cebu behind it and Negros ahead, and the line running down from that buoy is the whole of the dive. You take it hand over hand, and the current is the reason, not the depth. Underneath is blue with nothing in it to look at.
At 23 to 25 metres the top of the shoal resolves beneath you, and it is small: about twelve metres across, a plate you can swim the width of in under a minute. From its edge the sides fall away in every direction into a strait several hundred metres deep. There is no shallower ground anywhere on this site.
The lionfish are on the plate, in numbers, and large. Twenty in one place is what photographers come out here for. Frogfish sit on the rock and Spanish dancers cross it. Everything else happens outward. Jacks work the blue off the edge, with barracuda, mackerel, batfish, schools of blue triggerfish, and further out tuna, grouper and snapper. Guides here describe the fish as extremely on edge, which is a real property of an isolated shoal in open water and not something a coastal wall produces. Keep your eyes off the rock and into the water.
Then you go back up the line. There is no reef to drift onto and no wall to follow shallow, so the safety stop happens in mid water, in a current that runs to four knots with up and down components. That part takes real skill.
What makes it special
Every other dive in Moalboal happens on a wall you could swim to from a beach. This one sits ten kilometres out in the middle of the strait, and what changes is not the distance but what the animals are attached to. No reef, no coral, no drop off with a top to work back onto. A free standing shoal in open water collects fish that are passing through, so jacks, barracuda and mackerel arrive out of the blue instead of off a slope.
The lionfish are the part that belongs to this pinnacle alone. Every seamount collects passing pelagics; only this one gets described for its lionfish, and what the shops lead with is size and number. No other dive on this coast is described that way.
The last difference shows up on the bill. Moalboal shops price this as an extra, 200 pesos on top of what they already charge, and it is the only site in the area with a surcharge of its own. That is the plainest statement of what the dive is: not part of the standard day, and something you have to ask for.
Know before you go
Weather decides this one. It runs only when the surface is calm enough for a boat to hold a mooring in mid channel, and it is the first thing dropped from a schedule. Put your request in at the start of a week and you get two or three chances at it. Leave it to the last day and you go home without it.
Two shops put more than a card on the door. Advanced Open Water is the floor both publish, one adds nitrox certification on top, and the other wants a substantial number of logged dives behind it. The 25 to 30 metre working band on a site that costs an hour of boat time is exactly what nitrox is for, so take it if you have it.
Stay on the line, down and up. It is the only reference on this site, and the current is why every account of the descent has divers going hand over hand. Brief the down current on the surface: up and down components are named here specifically, and nothing underneath will stop anything. Carry an SMB and expect to hang your stop in open water.
Lose the plate and you are in blue in a current. It is twelve metres across.
Then the part that gets left until too late. This dive has the deepest working band, the strongest current and the longest boat ride on the coast, and the nearest recompression chamber is in Mandaue City, 82 kilometres and about two and a half hours by road with the boat leg in front of it. As of early 2025 only three chambers were working in the whole country. Insurance with hyperbaric cover is not optional here.
Why Dive Sunken Island
What makes this dive site stand out.
- Summit at 23 metres
The top plate is about 12 m across and the sides fall away out of sight
- Descent on a mooring line
The only structure and the only reference, hand over hand on the way down and up
- Currents to four knots
Up and down components as well as horizontal, the strongest anywhere on this coast
- Aggregated lionfish
Photographers come for them, often twenty in one place and large
- Priced as an extra
The only site in the area that shops add a surcharge for
Depth & Profile
Location
9.8587°N, 123.3442°E
Conditions & difficulty
Summary
Current runs 1 to 4 knots with up and down components, on a pinnacle with no bottom underneath it. The mooring line is the only reference on the descent and the only one on the ascent, so the safety stop happens in mid water. You are at 23 to 25 m from the moment you arrive and the dive has no shallow phase at all. The summit is about 12 m across, and losing it puts you in open blue in a current.
Safety considerations
What can go wrong here, and what divers do about it. Conditions change - take the briefing from the operator on the day.
- Current: One to four knots with up currents and down currents, on a pinnacle with no bottom under it.Descend and ascend on the mooring line, and brief the down current on the surface before anyone gets in.
- Depth: The dive starts at 23 to 25 m and has no shallow phase. The working band is 25 to 30 m and there is no shallower ground to move onto.Plan it as a short deep dive against gas and no stop time, and take nitrox if you have it.
- Orientation: The summit is about 12 m across and it is the only thing to see. Off its edge there is open blue in every direction.Stay within sight of the plate and the line, and carry an SMB for a mid water ascent.
- Marine life: Lionfish gather on a plate the size of a tennis court, often twenty at a time and large.Hover over the rock, keep off it, and give them room when the current pushes you across the top.
- Surface and boat traffic: The trip depends on a boat holding a mooring in mid channel, and it is the first thing cancelled.Keep slack in the schedule for weather, and accept that the boat may not go.
- Remote location: The deepest working band, the strongest current and the longest boat ride in the area, in front of an 82 km road transfer to the nearest recompression chamber in Mandaue City.Insurance with hyperbaric cover, conservative profiles, and a check that the boat carries oxygen.
Marine Life
Regulations
Tañon Strait Protected Seascape
This rests on what operators charge. No instrument sits behind it: which municipality's waters the pinnacle occupies has not been settled, so no ordinance has been shown to govern diving on it. What a diver pays here is what the shop charges: the municipal fee it bills on every dive, plus 200 pesos for this site. Moalboal's environmental user's fee and its diving ordinance cover Moalboal's own municipal waters, and the position published for this shoal is filed under the neighbouring municipality of Badian, whose own rules for divers have not been established. Confirm both amounts when you arrange the trip.
Frequently Asked Questions
How deep is Sunken Island?▾
The top of the shoal is at 23 to 25 metres and that is where the dive starts, not where it ends. The working band once you are on it is 25 to 30. Nobody publishes a maximum, because there is nothing to publish: the sides drop into a strait several hundred metres deep, so your gas and your computer set the floor of this dive, and the terrain does not. A flat figure of 25 metres circulates as the site's depth and it is the most misleading number on this page, because it describes the shallowest point of a dive that begins there and goes down. Plan it as a 30 metre dive.
What certification do you need to dive Sunken Island?▾
Advanced Open Water, and at two shops that is only the start of it. One publishes Advanced Open Water plus nitrox certification. Another asks for Advanced plus a substantial number of logged dives, which is a question of logged experience and not of a card. Every shop that runs the site calls it experienced divers only or the hardest dive in Moalboal. The reason is not depth on its own: it is a 23 metre arrival with no shallow phase, a current to four knots with vertical components, and a safety stop hanging on a line in mid water.
Why do dive shops charge extra for Sunken Island?▾
Because it is a separate trip and not part of the usual day. Ten kilometres out, 26 to 40 minutes each way by outrigger, and a boat that has to hold a mooring in open water. Moalboal shops add 200 pesos for it on top of whatever they already bill, and no other site in the area carries a surcharge of its own. Expect to pay it, and expect the trip to be dropped if the surface is not calm.
Which municipality is Sunken Island in, and does it change what you pay?▾
It is not settled, and what it changes is where the rules would come from, not what lands on your bill. The position published for the shoal is filed under Lambug in the municipality of Badian, and the boat ride out is described as heading in Badian's direction. Where the municipal boundary runs out in the strait is an open question. Moalboal's environmental user's fee and its diving ordinance apply to Moalboal's own municipal waters, so if the pinnacle sits in Badian's they do not reach it, and Badian has no diving regime we can point to. What is certain is the practice: the shops that run the trip bill their usual municipal fee on the dive and add 200 pesos for the site. Read that as what operators do, not as what an ordinance says.
How strong is the current at Sunken Island?▾
One to four knots, and the direction matters more than the top of that range. Up currents and down currents are named here specifically, on a shoal with nothing underneath it. That is why the descent is hand over hand on the mooring line and why the ascent is the same line in reverse. A diver who is comfortable in a two knot drift along a coastal wall can still find this uncomfortable, because there is nothing to hold position against and nowhere shallower to escape onto.
Will you see sharks, mantas or whale sharks at Sunken Island?▾
Sharks, sometimes. The occasional shark comes through out in the blue and nobody has put a species on it, so there is nothing to plan around. Mantas are not a Moalboal animal and one here would be a surprise, not a draw. Whale sharks in Moalboal are wild and occasional, most often met further north along the coast, and this pinnacle is not where anyone looks for them. Nothing in the area is fed or provisioned. The reliable animals here are the lionfish on the plate and the jacks off its edge.
Is Sunken Island worth the extra cost?▾
If you came to Moalboal for the coastal walls and the sardines, it will not feel like value: more money, a longer ride, and a short dive at depth on a plate the size of a tennis court. If you want open water and animals arriving out of the blue instead of sitting on a reef, there is nothing else like it within reach of this coast. Shops run it rarely and only in calm weather, so treat it as a bonus on a Moalboal week and not a fixture of one.
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