Topic: Giant Aquarium for Scuba Divers
The Underwater Park is a Technological Challenge

Date: All Year

Summary:
The excavation is 120 metres long, 60 metres wide and seven to eight metres deep. With a volume of 30,000 cubic metres this pond on the premises of pond specialists NaturaGart will become Europe's largest 'aquarium'.
The special thing about this construction site is that the Underwater Park is not only for fish, but also for scuba divers, who will find the best diving conditions.

Most bodies of water get cloudy through in-washing iron and swirled up sediment. Visibilities are below one metre. Visibility improves dramatically if the pond is sealed against ground water with a liner and the sediments are regularly filtered out. This way visibilities of 10-20m can be achieved in sweet water.

This is exactly what is being built for the super-pond in Ibbenbüren. 17,000m² of liner and more than 40,000m² of thick fleece ensure that the pond keeps its water.

In order to protect this delicate seal from damage, the entire floor was covered with a layer of concrete. On top of that artificial reefs and caves are being built to enhance the divers' experience in this scuba paradise.

Expansion:
The filtered clear water park meets a demand that outsiders easily underestimate: There are more than 2 Million scuba divers with compressed air experience in Germany. 160,000 of these would travel more than 200 kilometres for a 'proper' dive.
To this has to be added a rising interest in the underwater world: deorative aquariums are in high demand.

The pond builders at the Teutoburg Forest are really only increasing dimensions: The fish no longer swim in an aquarium, but rather the visitors sit inside a glass boat.

From here they will be able to observe the underwater wonder-world of water lilies and water milfoil forests. Drawn by a cable-system they encounter huge sturgeons and glide past vast caves, a sunken temple and a stranded wreck.
Never before has an underwater world of these dimensions been built for this purpose. The technological feat is only possible because NaturaGart has such outstanding expetise in planning and building large pond systems. Every year NaturaGart helps plan and build thousands of swimming- and fish-ponds. The company's leading modular filtration technology is also going to be used for this large pond.

The specialists at NaturaGart decided to install two separate sealing layers. Even in the unlikely case of damage the pond is prepared: Between the sealing layers lie swelling types of clay that would get washed to the leak and would then stop up the fleece - the pond repairs itself.

NaturaGart does not only regard the Underwater Park as a spectacular reference project. The hands-on experience gained through building such large installations will benefit their clients, too.

Details about the Underwater Park:

Length 120m
Width: max. 60m
Depth: approx. 7m
Volume: approx. 30,000m³
Gravel for bed: 2,000t
Fleece 'Vlies900': 42.000m²
Liner, 1mm: 17,000 m²
Structural steel, 10 mm: 71,000m
Steel mesh: 1,000m²
Concrete (to date): 2,000m³
Rocks for constructions (to date): 6,000t
Length of caves: 250m
Largest cave dome: 6m
Cliff surface: 4,000m²
Land base: 1,000m²
Real construction time: approx. 2 years

Images:
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Image rights:
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Photo: NaturaGart 

The bed of the more than 100m long excavation was stabilised with over 1,000 tons of gravel.	The construction site lies four metres underneath ground water level. A bulldozer nearly sank in an old bomb crater.	The bed is ready. Fleece has been laid out on the banks.
	The company's premises from above: Nature and ponds attract thousands of visitors every year.
The excavation is finished: Fleece and liner are being laid.		Because of their size the liner and fleece bobbins are very heavy: A bulldozer helps to unroll them.
		The various layers of the pond guarantee its stability and durability.
Structural steel and concrete cover the liner to distribute loading.		A bed of concrete is made on top of the liner and steel.
	The walls are covered with large stones and back-filled with concrete.
Jagged, reef-like constructions are built. Later these 'works of art' will be under water.	Construction of the approximately 250m long system of caves: A paradise for scuba divers.
Fish and scuba divers alike will love the caves.		The caves and grottoes are made of steel and natural stone.
The bulldozer helps positioning the large natural rock.	Even now one feels like the caves are a different world.	Aerial image of the western shore: The structural steel constructs for the caves are over 100m long.
Map of the Fixtures: The underwater buildings make diving an experience.	February 2004: The first reef wall has reached its final height. In the background the temple 'Atlantis'.	Most caves are finished. Reef walls split the park into separately themed areas. The last liners are laid in the bulldozer entrances.
The first pillars for an 'antique temple'.		The roof surface is about 250 square metres and is being concreted.
Cornices are decorated with figures inspired by Egyptian originals.	The finished temple looks like a much larger compound that has been covered by a stone avalanche.