Artificial reefs in beautiful Calatagan is a successful restoration story. A story of Community, Conservation, and Coral Revival. In this historic coastal fishing town, the once-devastating effects of unchecked tourism left scars on the ocean. But today, a glimmer of hope shines through as re-education and community efforts pave the way for a more sustainable and respectful approach to tourism.
Nestled along the southwestern coast of Batangas, the peaceful town of Calatagan hides a unique underwater marvel known to only a few divers and marine conservationists: the Underwater Pyramids of Calatagan. These man-made reef structures, resembling ancient pyramids resting beneath the sea, are not the remnants of a lost civilization but the result of a community’s unwavering commitment to protect and restore the marine environment.
Artificial reefs are important tools to bring back life. Efforts to rebuild and restore marine ecosystems around the world utilize man-made structures, often constructed from sunken ships, concrete blocks, reef balls, old tires, or even decommissioned subway cars. Designed to mimic the complexity and function of natural reefs, they provide a stable surface for marine organisms to attach to. Artificial reefs create new habitats in areas where natural reefs may be degraded or absent. Over time, these structures become colonized by algae, corals, and sponges, forming the foundation for a thriving underwater ecosystem.
But not all artificial reefs are conducive to healthy marine ecosystems. Poorly planned or improperly constructed reefs can do more harm than good. For example, artificial reefs made from materials that degrade, leach toxins, or are unstable—like old tires or poorly treated metals—can pollute the surrounding waters and endanger marine life. Learn more about it a 2 Million dollar budget to clean out the tires by Florida Governor Charlie in Florida back in 2007 Artificial reef in Fort Lauderdale.
Placement is also critical; if structures are dropped in unsuitable locations, they may smother existing habitats, alter natural currents, or interfere with the behavior of native species. In some cases, artificial reefs have even been used as a way to dispose of waste under the guise of conservation. For artificial reefs to truly benefit the environment, they must be designed with ecological sensitivity, use non-toxic, durable materials, and be part of a broader marine management strategy that includes monitoring, community engagement, and protection of nearby natural reefs.
Which is why the Pyramid of Calatagan is a gigantic marvel to behold. Conceptualized in 1999 a prominent Filipino Don collaborated with Barangay Bagong Silang and volunteer divers to save his beloved Calatagan. This success story took more than ten years to develop into a full-fledged environmental success.
A Vision for a Healthier Ocean
In the late 80s, the coastal waters of Calatagan faced mounting challenges. Overfishing, destructive fishing practices like dynamite and cyanide use, and unchecked tourism have left local reefs damaged and marine biodiversity in decline. Seeing this firsthand and deeply passionate about marine life, the late philanthropist Don Vicente Madrigal-Warns dedicated his later years to restoring fish populations in the area.
The solution they envisioned was both innovative and rooted in tradition: to create artificial reefs. They began with used tires, but processed rubber uses sulfur, heavy metals, accelerants, and stabilizers that are harmful to the ocean. And the fish naturally stayed away.
Then they tried again with cement. But not all cement formulas are suited for long-term underwater use. Regular concrete cracks or degrades over time due to saltwater exposure. It also becomes brittle and less stable, especially if not reinforced properly.
Calatagan is an entryway to the Verde Island Passage. The passage is known to have one of the strongest currents in the Philippines due to the Venturi Effect. So even at 65 feet below sea level, the cement blocks degraded.
Using the Dead to bring back Life
The article of Philstar wrote,
It was on June 24 last year that Warns and Villanueva, over a few bottles of beer, thought of putting up pyramids. “Pyramids were built millions of years ago in Egypt. They are still standing until now. So, we made some research and a feasible study and that is how we came out with the pyramid reefs,” Warns said.
So in the form of pyramid structures using locally available materials. The idea was inspired by the natural way coral and marine life flourish on shipwrecks and other submerged structures. With the help of marine biologists and local government support, the project began to take shape.
The pyramid reefs were formed out of dead corals beached infront Warns’ rest house. Villanueva said they recruited local folks and children during weekends for volunteer work by collecting the dead corals. -philstar article by Christina Mendez-
The son of another trailblazer, the second female senator of the Philippines, Don Vicente helped design the innovative pyramid structures now resting on the seabed. Built using dead corals, cement, and bamboo crossbars, these pyramids function as artificial reefs, providing sanctuary and breeding grounds for fish. Over time, they have become vital to the rejuvenation of Calatagan’s marine ecosystems.
Further developments in the project were noted in 2003, when nine 30-foot-high pyramid reefs had been established, marking significant progress in the marine conservation efforts in the Philippines.
Building the Pyramids
Constructing an underwater reef isn’t a simple task. Each pyramid was carefully assembled using recycled dead coral blocks, with each block weighing approximately 75 kilograms. These blocks were not live corals taken from the ocean, but pieces already broken or dead, collected from nearby shores. This approach ensured the project did not contribute further to reef destruction.
Volunteer divers, many of whom were local fishermen trained in basic scuba diving and reef conservation, took part in the labor-intensive work. The pyramids were submerged and constructed at depths of around 65 feet, in sandy areas devoid of coral cover. The structure’s pyramid shape provided a sturdy, current-resistant base with multiple surfaces for coral larvae to attach and grow.
A Community-Led Movement
What made this project unique was not just its outcome, but its inclusive process. Community engagement was a central element of the initiative. Children and local residents were involved in collecting coral blocks, learning about marine biology, and understanding the vital role coral reefs play in their lives.
The project also brought economic opportunities to the community. Local laborers were hired to mold and transport coral blocks. It wasn’t just an environmental effort; it became a source of livelihood and pride for the people of Calatagan.
One of the most touching parts of the project was the dedication of a special pyramid adorned with a cross. It serves as a memorial to Barangay Captain Sixto Atienza, a staunch defender of the marine environment who paid the ultimate price for his advocacy. Atienza was known for his fearless enforcement of anti-illegal fishing laws, and he was tragically assassinated for his efforts. His memory lives on through this underwater monument, reminding divers of the cost of protecting our oceans.
The Ecological Impact
More than a decade after the first pyramids were placed underwater, their impact is clearly visible. Once barren sandy seabeds are now teeming with life. Soft and hard corals have colonized the structures. Small reef fish like damselfish, wrasses, and gobies dart among the crevices, while larger species such as groupers and snappers have returned.
Sponges, tunicates, and sea fans also thrive on the structures, contributing to the rich biodiversity. These artificial reefs have become important nurseries for juvenile fish, helping replenish nearby fishing grounds. The resurgence of marine life has even attracted larger pelagics such as jacks and trevally.
For scuba divers, the underwater pyramids offer a surreal experience. Swimming around the symmetrical structures, watching marine life interact with them, and seeing the dedication etched into the structures is both educational and humbling. These are not your typical reefs — they are living proof of human effort to heal what has been broken.
Educational and Tourism Potential
Aside from conservation, the pyramids have opened up opportunities for sustainable eco-tourism. Calatagan is gradually becoming a destination for divers who seek off-the-beaten-path adventures. Unlike the more popular spots like Anilao or Puerto Galera, Calatagan offers a more serene and personal underwater experience.
Dive shops and local tour operators now offer guided dives to the pyramids, incorporating marine education and conservation awareness into their briefings. Divers are encouraged to take part in reef monitoring, participate in clean-up dives, and share their experiences to raise awareness.
For students and environmental groups, the site has become an open classroom. Marine biology students from nearby universities conduct field studies here, observing coral growth, fish populations, and the effects of artificial reef structures.
The Challenges Ahead
Despite its success, the Calatagan pyramid reef project still faces challenges. Climate change-induced coral bleaching, illegal fishing activities, and insufficient enforcement of marine protected areas remain concerns. The project’s success has highlighted the importance of community involvement, but it also underscores the need for continuous education, funding, and government support.
Additionally, there’s a need to scale up the initiative. Neighboring coastal areas could replicate the Calatagan model, but this requires training, coordination, and logistical support. There’s also the challenge of balancing eco-tourism with reef protection. While divers bring income, increased traffic must be managed carefully to prevent damage to the delicate marine ecosystem.
A Model Worth Emulating
The underwater pyramids of Calatagan are more than just structures beneath the sea. They symbolize resilience, collaboration, and the power of grassroots conservation. In a world where coral reefs are disappearing at an alarming rate, this project stands out as a beacon of hope and a reminder that communities can be powerful agents of change.
For divers, visiting the Calatagan pyramids is more than a dive; it’s a journey into a story of transformation. It is a chance to witness how a determined group of people turned grief, loss, and environmental decline into a vibrant, living underwater sanctuary.
Whether you’re a scuba diver, conservationist, or simply someone who loves the ocean, the story of the Calatagan pyramids invites you to reflect on the roles we play in protecting the sea. And perhaps, it might just inspire the next wave of reef builders, ready to take action for our planet’s blue heart.
Dive Tip: When diving in Calatagan, practice good buoyancy control to avoid touching or kicking the pyramids. These structures are fragile habitats and every diver’s care contributes to their longevity. If you want to learn how to hover effortlessly and improve your trim, consider taking the PADI Peak Performance Buoyancy Specialty Course before your visit.