© Triton Submarines LLC

Diving down to the Great Barrier Reef

Climate change is jeopardizing the world's largest coral reef – nearly 93 percent of the corals are threatened with extinction. Thanks to PLEXIGLAS®, the world’s attention can be drawn to this emerging disaster.

At around 65 kilometers wide and 2,300 kilometers long, the Great Barrier Reef is gigantic. It is the largest living organism on our planet and the only one that can be seen from space. The biodiversity bustling around this area is just as large – there are more than 1,500 species of fish, around 600 species of coral and 30 different species of whale and dolphin. But this precious underwater universe is in danger.

The pale death

Nearly half of the scintillating coral splendor is already dead – destroyed by coral bleaching. The phenomenon results from water temperatures that are too high. Coral needs algae to live; they not only create the variety of colors, but also provide the coral with nutrients. When it gets too warm, the algae start to secrete toxins. The coral rejects the algae, calcifies and turns pale. A large part of the damage can still be prevented, as coral can recover from a minor bleaching event. In order for this to happen, however, the water temperature has to fall and the water quality rise again – and as quickly as possible.

Show off what needs to be protected

The award-winning British filmmaker and naturalist Sir David Attenborough hopes to raise awareness of the danger to this sensitive ecosystem with a large-scale campaign. Working together with the BBC and the Natural History Museum in London, he is bringing the underwater world of the reef to TV viewers and the internet, for example by taking visitors to the Natural History Museum in London on a virtual reality dive to the Great Barrier Reef.

Like a fish in water thanks to PLEXIGLAS®

Recording the unique nature scenes using 3D technology required a submersible with a dome as clear as glass and as strong as steel in order to withstand the high pressure under water. This presented a challenge for the submersible manufacturer Triton. PLEXIGLAS®, the branded acrylic from Evonik, was literally the last hope for Triton Submarines. Several attempts by other vendors using another manufacturing technique were just not reliable enough and did not yield the quality needed. “There was no other company in the world we could trust with this pioneering feat of technology. After all, we wanted to build the largest sphere of acrylic ever made to provide an unrestricted all-round view,” explained Patrick Lahey, Managing Partner of the American submersible specialist Triton Submarines LLC.

Introducing Triton submersibles: All aboard!

As adventurous as an expedition

Producing the huge PLEXIGLAS® sphere became an expedition of its own – albeit one that took place at Evonik in Darmstadt and not in the South Pacific.

“We had already produced glazing for several submersibles, but never with the curvature of a sphere, so we had to come up with a totally new technology,” remembered Wolfgang Stuber, specialist in specialty glazings at Evonik. This is not something that can be accomplished overnight. Working closely together, Evonik and Triton Submarines invested one and a half years of development time into the project. Unlike in the previous models made for Triton by other companies, Stuber and the experts from Heinz Fritz Kunststoffverarbeitung decided not to cast the branded acrylic, but to mold blocks of PLEXIGLAS® into hemispheres. Two of these hemispheres were then bonded together. “Of course, we had to develop the adhesive ourselves, too. Until then, an adhesive that could hold acrylic together under such extreme outside conditions and still be nearly invisible didn’t exist,” said Stuber.

Two become one

The hemispheres were reworked, sanded, polished and bonded together into a sphere by Evonik’s processing partner Heinz Fritz Kunststoffverarbeitung. The sphere has a diameter of 2,100 mm and a wall thickness of 166 mm. It weighs 2.2 metric tons, and is approved for diving to depths of 1,000 m. The PLEXIGLAS® hollow sphere thus allows an unrestricted all-round view while also serving as a protective pressure hull for the passengers.

© Evonik

Evonik also had to acquire individual certificates for both the hemispheres and the adhesive from Germanischer Lloyd – a similar organization to TÜV for cars. After all, everything related to shipping is subject to the strictest quality controls and classification regulations. “The effort was certainly worth it,” said Lahey with pride. “The PLEXIGLAS® sphere is so clear that it becomes nearly invisible when submerged in water! We’ve already had passengers reaching for the inner wall to make sure that it’s really there.”

Greenhouse effect as clear as glass

Thanks to the transparency of the submersible dome, the Triton 3300/3 was able to bring both the treasures of and the damage to the Great Barrier Reef to the eyes of the world. Only the completely unhindered 360-degree view enabled the impressive images that allow viewers to experience the underwater world up close and personal.