Fascinated by the fabrication and installation of rockwork in the Two Oceans Aquarium, Brand and Sustainability Manager Helen Lockhart chatted with Operations Manager Tinus Beukes, Senior Aquarist Pierre de Villiers and Mike Behr, owner of Wild Exposure.

Southern Africa has one of the most fascinating coastlines in the world. From rocky crags pitching into dark blue ocean water to kilometres of sandy beaches, this coastline is spectacular and is home to a rich diversity of fauna and flora.

As seen on The Wild Ones, every Sunday at 4pm on M-Net 101.

One of the challenges of the Two Oceans Aquarium is to design exhibits which replicate the inhabitants’ natural habitat as closely as possible and to showcase the beauty of this natural habitat. This is no mean feat – in fact according to Tinus Beukes, our Operations Manager, it is really difficult, if not impossible, to mimic nature. Building rockwork takes technical knowledge, but also considerable artistic flair!

In the early days of the Aquarium’s construction back in 1994/1995 large artificial rocks made of fibreglass were created from moulds of real rocks to ensure the authenticity of the large exhibits such as the Predator Exhibit and the Kelp Forest Exhibit. Crushed shells and sand were blasted on to the outer layer of the ‘rocks’ to enhance the effect of realism.

From left: Lex Fearnhead, first Managing Director of the Aquarium; the late Duncan Temple Forbes, the fabricator of the fibreglass rocks; and Sheryl Ozinsky, the first Marketing Manager of the Aquarium.

In Chapter 35 of his book Crazy! Adventures of a Marine Biologist Dr Patrick Garratt, our previous CEO, writes about some of the early challenges of fabricating and installing rockwork that would work for both the animals and the visitors. Among the challenges were designing rockwork in the Predator Exhibit which would accommodate fast-swimming tuna (they need “laminar flow” which is “an even, streamlined flow of a liquid without any turbulence”), building moulds from natural rocks (and getting permission from Table Mountain National Park), finding the “right” rocks from which to make the moulds (Pat talks about sandstone rock being too complex and detailed so they used the granite outcrops found off Camps Bay and at Boulder’s Beach near Simonstown as inspiration for the original rockwork in the Predator Exhibit), and swaying rockwork in the Kelp Forest because the framework to which the fibreglass rocks were initially attached was too light to cope with the surge once the exhibit was filled with water.

Kelp Forest rockwork – the original rockwork made from fibreglass.

Building large-scale rockwork for Aquarium exhibits has come a long way since those early days. The rockwork for our I&J Ocean Exhibit and the revamped Predator Exhibit and Kelp Forest Exhibit was completed by Wild Exposure, a company which specialises in the building of artificial rockwork.

I chatted with Mike Behr, the owner of Wild Exposure, about some of the questions which came to mind while watching Episode Two of The Wild Ones.

Helen Lockhart: What is the longevity of the rockwork?

Mike Behr: We normally guarantee our rockwork for 10 years. But we have been building rock structures for 20 years now and have had no recalls. Concrete gets stronger over time so it would be safe to say we can give a lifelong guarantee on our work.

HL: One of the issues with plastic is that it has the potential to leach toxic chemicals and to attract toxins in the oceans. Is there any danger of toxins being leached into the water of our exhibits?

MB: The plastic used is PVC and polycop pipes, the same pipes that supply water to the exhibits and the same pipes that supply drinking water to households across the globe. Safe to say there is no chance of toxins being released unless it catches fire.

HL: Will the inner structure, which is made of PVC pipes, cable ties and mesh, buckle over time with the weight of the cement and the water?

MB: In water, the structure does not exert as much weight as one thinks. Nevertheless it will support itself on land as well. We have used the same method to build structural supports for walls and to hold back soil in embankments and retaining walls. It was also used in trade shows to showcase the 4x4 capabilities of trucks that drove over our rocks as a demonstration. These same rocks are still being used at the same NAMPO trade show eight years later.

HL: How and when did you develop this technique?

MB: This method was developed by us as an alternative to using reinforcing steel in 2004. This was at the uShaka Marine World in Durban. There was concern that the steel in rockwork would affect the sharks’ magnetic field and senses. We were asked to come up with an alternative. After trying out several ways to build rock using polystyrene blocks (messy) and brick walls clad with rockwork (difficult to shape), one of our staff suggested using some electrical conduits that were lying around on site. This worked perfectly. Even though they are more expensive than the steel equivalent they are easier to bend and shape. Since we are all getting older and weaker this comes in handy sometimes! We now use this method exclusively when working near or in a marine environment as reinforcing bar spalls and splits the rock when rust sets in.

HL: Where else has this technique been used?

MB: In the Ambassador Tank in Dubai, Bazaruto Island resort Annantara in Mozambique, Sun International waterparks - Sun City, Victoria Island (Nigeria). Wild Coast Sun…

HL: Does your team have any specific qualifications? E.g., are they geologists? How do they understand and appreciate how to create natural-looking rockwork?

MB: I was always fascinated by rock and its shapes as a rock climber. My carving staff all have a background in working with companies in the UAE as well as an element of artistic talent. We continually discuss new and different ways to make our rockwork stand out from other suppliers. Our team are always proud of their achievements and even more so when they are complimented on the work.

Can you believe that this ... 

Once looked like this?


Many of the smaller exhibits in the Aquarium incorporate what we refer to as “live rock”. These rocks have been collected from the environment – either from the ocean or even from coastal dune areas, e.g. the sandstone rockwork in our Eel Exhibit was collected from Koeberg Nature Reserve, and the dark rock in the Midnight Zone exhibit came from one of I&J’s trawls. Many of these rocks have been used over and over again in the exhibits – Tinus reckons he can identify which pieces of rock have been used where over the years.

Senior Aquarist Pierre de Villiers scuba diving amongst what is not, contrary to what you might think, real rocks.

Our aquarists have also built rockwork – one such example is the rockwork in the Cold Reef Exhibit in the Skretting Diversity Gallery. I chatted to Senior Aquarist Pierre de Villiers, who created this rockwork.

HL: Tell me about the process of building this rockwork?

Pierre de Villers: I was first sent to Durban’s uShaka to learn about rock building. While I could have used the same structure that Mike used in our larger exhibits (the PVC framework and the mesh) I needed to build something that the aquarists could climb on and that would also withstand the pounding of a wave.

First I built the shape using cinder blocks and bricks. When I was happy with the general shape I started applying the cement, which has lime mixed into it. I had to work pretty fast as it was important not to let the cement dry out too much. It’s easy to carve cement when it’s wet to create the cracks and crevices of rock, but if it dries out too much then you have to use a mini-jackhammer! In order to enhance the overall effect I made latex impressions – “stamps” is a better word – from the granite boulders at Granger Bay. Using a release agent I applied these stamps to the cement to create the indentations that I wanted.

The final stage involves painting the cement with a water-based paint. I started with the blacks and then used lighter colours to create “natural"-looking rocks.

HL: What about the lime leaching into the water?

PdV: Yes, this is something we had to take into consideration. So before we added the fish to the exhibit we first had to let the tank run for about a week. Fortunately the Aquarium is on an open system – meaning we get fresh seawater coming in all the time, flushing the exhibits. If you are building rockwork like this for your tank at home you need to run the tank a lot longer before adding the fish otherwise you’ll kill them with the lime.


At the end of my chat with them Tinus and Pierre both encouraged me to look up the Japanese art of stone and rock appreciation known as Suiseki. Suiseki is “the Japanese art of stone appreciation, which values aspects like stability, longevity and immortality. Formed through time by wind and water, stones can take several sizes and shapes, reminding us of natural objects”.

Suseiki - the art of stone appreciation. Photo courtesy Italian Association of Suseiki Lovers

Suiseki is used alongside the art of bonsai and was also used in the aquascape creations by the late Takashi Amano, one of which can be seen in the Oceanário de Lisboa, the oceanarium in Lisbon. The Oceanário de Lisboa’s temporary exhibition, “Forests Underwater by Takashi Amano” features tropical forests inside a magnificent aquarium.

There is more to rock than meets the eye!

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