Not a world record, but close 
National Marine Aquarium, Plymouth, Devon, U.K.
In March, one of the world's biggest windows was hoisted into place in the aquarium, forming a key part of a four-million-pound extension. It took a whole morning to lower the 30-foot [9-m], four-ton acrylic pane into position at the base of a 10.5-metre tank, the deepest in Europe. Visitors will walk underneath the four-inch-thick [100-mm] window, looking up at 2.5 million liters of water on the far side of the pane.
The new window proved to be a perfect fit. The american company providing the window, said: `There's only three companies in the world that can make acrylic panels to that size.' When asked how long it will last, they had a very simple answer: `Forever. It's plastic. Unless it gets damaged, then it would have to be repaired.' But there was no damage whilst the window was being put in place. Something else that went smoothly was the craning in of some exhibits that will stand alongside the new tank – life-sized working models of whales. Real sea creatures will follow, and the extension to the National Marine Aquarium could be open to visitors by late May.
Hydrosight Corp. acknowledges the quality and the engineering achievement, even so not involved in this particular project.
