Only an hour and a half by fast boat from Bali, Indonesia, Lombok’s northern islands, or Gilis, are still just off the beaten track, despite their increasing popularity with backpackers, honeymooners and travellers looking to get away from it all.

No more than seven kilometres wide, Gili Trawangan is a place where Lombok’s traditions merge with Western style boutique shops, where bamboo beach bars sit next to trendy cafés, and basic bungalows share their sandy lanes with five-star villas. No cars, motorbikes or dogs are allowed on the island, making this small patch of sand a quiet and natural tropical paradise. Yet this island getaway is also the location of one of the world’s most intensive and futuristic reef restoration programmes – the Gilis are now home to a staggering total of 119 electric reefs – one of which is solar powered.

Indonesia’s waters are full of life and colour; the collision of the Indian and Pacific Oceans results in a wealth of fish and coral diversity, and the diving in Indonesia is considered by many to be the best in the world. Yet in many places, destructive fishing practices, combined with El Niño cycles, have caused enormous damage to Indonesia’s underwater heritage.

Lombok’s three famous northern Gilis sit closely, side by side. Huge volumes of water rush between them, creating incredibly strong currents that bring with them an abundance of life. Here, it is possible to see some of almost everything that diving in Indonesia has to offer – from vibrant nudibranchs and tiny pygmy seahorses to large reef sharks, thriving populations of turtles, and transient mantas. In the shallows, there are gardens of hard and soft corals, and endangered hawksbill and green turtles being cleaned by small butterflyfish and cleaner wrasse. Deeper waters harbour resident whitetip reef sharks, and, during the full moon, the reefs are subjected to the boisterous attentions of a school of bumphead parrotfish, which, like an otherworldly herd of cows, graze on the corals and play amongst the bubbles of divers.

Installing Biorocks takes training, a team of volunteers, and a certain degree of physical ability (Image © Steve Woods)

Yet the Gilis also bear their share of scars. For many years, they were fished using dynamite, and in some  places, you can still find patches of coral rubble on which nothing will grow. Rubble shifts with the currents and waves, making recolonisation by coral recruits very difficult. Without help, these reefs could take many decades or more to recover. On land, the effects of this annihilation can be seen with beaches eroding away, having lost their essential offshore protection from wave action – the coral reefs.

In 2004, Delphine Robbe and the Gili Eco Trust set out to change this, to rebuild the area’s marine biodiversity and biomass, starting at the very foundation of life in the ocean and restoring the islands’ coral reefs. Teaming up with coral ecologist, founder of the Global Coral Reef Alliance and creator of Biorock reef restoration technology, Dr. Thomas J. Goreau, they created the first living artificial reefs in the Gilis.

After only a few days a layer of calcium carbonate develops, coating the steel structure and providing an ideal substrate for coral recruits (Image © Foued Kaddachi)

Biorock reefs are steel structures that employ the principles of electrolysis – a process by which electrical currents cause substances present in a liquid to come out of solution. Electrolysis requires one positively charged electrode, the anode, and one negatively charged electrode, the cathode. When a positively charged anode and a negatively charged cathode are suspended in seawater and an electric current flows between them, calcium ions combine with carbonate ions and form calcium carbonate, which adheres to the cathode.

A Biorock’s steel structure is, essentially, a cathode, and, once the current starts to flow, it soon becomes covered in calcium carbonate, or limestone, a mineral that has literally crystallised out of the water. This mineral is almost identical to the substance that forms coral skeletons, and is an ideal substrate for corals to colonise.

The Biorock project engages and mobilises a large cross-section of the diverse community of the Gilis. This structure was installed in 2006 (Image © Wolf Hilzberg/ Gili Eco Trust)

Biorock structures can be covered with coral fragments that have been detached from their mother reefs due to storm action, or that have been grown for the purpose. Once colonies take hold on the structure, their skeletal growth is also supported. This means that more energy can be devoted to reproduction, and to resisting stressors.

As time goes on, the structure matures and develops– coral colonies lend increasing structural complexity and the reef develops into a paradise for fish to inhabit for feeding, shelter and reproduction. Corals planted on these structures can grow up to six times faster than corals in the surrounding area and have also been shown to be a lot hardier. Every year, seasonally warm waters raise the sea temperature around Gilis to over 30˚C for extended periods of time. The corals on the Biorocks have proven to be a lot less susceptible to stress and bleaching than other reefs around the Gilis.

But the positive effects of this technology do not seem to be localised. Not only does the mild electric current stimulate the growth of corals attached to the structures, it seems that within a field of up to 15 metres around each Biorock, other corals benefit. In the Gilis, previously uninhabited slopes surrounding the structures have now become lavish coral gardens. And, just like natural coral reefs, Biorock reefs are also extremely successful in dissipating wave and current energy, and are helping to stem coastal erosion – beaches are returning.

The reefs around the Gilis now demonstrate areas of absolutely pristine corals and a healthy abundance of fish species. There is still an ongoing campaign to turn the Gilis into a Marine Protected Area, and with good reason – large areas of the reefs here are covered with a rare type of blue coral, found in few other places in the world in such healthy abundance.

1. Hawksbill and green turtles (such as this one) are unusually abundant on almost all the dive sites around the Gilis. Divers regularly report sightings of more than 10 per dive on some sites (Image © Vinny Turner)

Even though the reefs around Gilis are healthy, colourful and diverse, growing development on the islands has led to an increase in anchoring and associated damage, and an ever-greater need for restoration projects such as Biorock. In recent years, the warm, clear, fish-filled waters have led to an incredible boom in the dive industry here. Slowly, more and more people are beginning to catch on that there is fantastic, yet hassle-free diving right off the beach. Protecting the natural resource that underpins this industry is vital.

I had intended to visit Gili Trawangan for about six weeks after finding out about the Biorock Reef Restoration Programme carried out through Trawangan Dive and the Gili Eco Trust. But after completing my two weeks of training, learning how the Biorock technology works and how successful the project has been around the Gilis, I swiftly made it my aim to stay and volunteer for as long as possible.

To enrol on this reef restoration course, students need little or no knowledge of Biorock, or any scientific background for that matter. All they need is a healthy desire to give something back to the ocean. In the first week, we trained in coral identification and learned how to recognise a whole variety of sponges, algae, fans and feather stars. In the second week we began the gruelling task of designing, measuring, cutting and welding locally sourced steel in the heat of a tropical rainy season. We installed 32 Biorocks, which, when put in place, created the form of a huge manta ray. Creative, yes, but, more importantly, this was to be the very first solar-powered, 100-percent sustainable Biorock reef.


Getting there:

You can get to the Gilis via Bali or by flying directly into Lombok from Jakarta. A number of fast boats leave from Bali’s Padangbai, Nusa Lembongan and Sanur; some of them go via Senggigi. The fast boats take around an hour and half. If you’re arriving in to Mataram, you will need to take a bus to Pemenang and from there take a cidomo (horse drawn cart) to Bangsal harbor. Public boats from Bangsal harbour to the Gilis run between 8am and 5pm every day, and only leave when they are full.

Equipment and training:

Diving in the Gilis is suitable for every level, with a number of IDC centres offering courses up to Instructor. To take part in the Biorock workshops divers should be Advanced Open Water certified or higher.

Best time to dive:

Water stays a warm 28°C and above year round and between the months of March of May the visibility can reach up to 40 metres. Currents are stronger from July to September in the dry season, bringing sharks and schools of pelagic trevally and barracuda. August winds bring waves perfect for surfers.

More information:

To find out more on the Biorock workshops, or the one day PADI Biorock Speciality course, contact

Read the rest of this article in Issue 5/2014, AA No.79 of Scuba Diver magazine by subscribing here or check out all of our publications here.

Post a comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.