Aquariums & Specialty glazing
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When pool dreams become a reality

With an ocean view, in the garden, or at dizzying heights: The Dutch pool constructors from Underwater Windows create unique swimming pools with PLEXIGLAS®.

For many, diving into the cool water and unwinding is the height of relaxation. The times when swimming pools were just a tiled hole in the ground are long gone. A lot of modern pools are now unique designer pieces. Underwater Windows from the Netherlands is a company which helps turn these pool dreams into reality. “This is not just a job for us, it is our vocation,” says Managing Director, Mark Hoentjen.

Many reasons for PLEXIGLAS®

He and his team have used colorless PLEXIGLAS® to create the transparent elements of their breathtaking swimming pools for eight years. In 2017 alone, the specialists used approximately 25,000 kg of the brand acrylic glass. So why does the team from Underwater Windows use PLEXIGLAS® so much? “There are two main reasons. The first is the excellent material quality, the second, the fantastic support from the specialists at Röhm,” says Managing Director, Mark Hoentjen.

One example of this is the excellent packaging in which the product is delivered. This may only be a small thing, but it strengthened the trust placed in Acrylic Products at Röhm as a supplier from day one – after all, a fabulous pool needs a flawless base product.

There is another reason to use PLEXIGLAS®, which is of particular importance for the pool constructors: The 30-year guarantee against yellowing. PLEXIGLAS® has UV protection inherent to the material and thus only displays minimal yellowing values, which are invisible to the human eye, even after three decades – an important factor for the designer pools constructed by the Dutch specialists.

Stylish ambience

This pool in a private residence in Marbella, Spain, impresses through its harmonious integration in the total ensemble of garden and terrace. The two 60 mm-thick PLEXIGLAS® blocks are glued together at the corners and provide an undistorted view into the pool, while easily withstanding the water pressure.

© Underwater Windows, The Netherlands

Fabulous double pool

This double pool in Bompas in southern France was built as a relaxation area in the spa of a private residence. The window is made from an 80 mm-thick block of PLEXIGLAS® GS and is so transparent that the stairs leading to the water of the upper pool can be seen. An overflow system lets the water flow from the upper level into the main pool, while the sun takes on the role of a heating element.

© Underwater Windows, The Netherlands

Pool construction at the highest level

This pool at a dizzying height is a real highlight. A PLEXIGLAS® sheet easily sustains the water pressure, while swimmers can enjoy a refreshing dip in the bright sunshine.

© Underwater Windows, The Netherlands


If you think that swimming pools can only have straight edges and sharp corners, think again. The curved end of this swimming pool on the roof of an apartment building shows the possibilities PLEXIGLAS® can offer pool constructors, such as Underwater Windows.

© Underwater Windows, The Netherlands

Unbreakable and glued invisibly

Hoentjen and his team only use PLEXIGLAS® GS for their pools, in thicknesses ranging from 30 mm to 130 mm. Compared to glass with the same thickness, the brand acrylic glass displays lower light refraction and thus provides a better view into the pool. It is also significantly more durable and available in different formats. “80 percent of the time, we only use 5 m by 2 m blocks,” says Hoentjen.

Larger-scale projects require correspondingly larger panes. The specialists use a special adhesive to join multiple PLEXIGLAS® blocks together. This procedure generally takes place at the Underwater Windows head office in the Netherlands. “When the final dimensions are too large for the product to be transported by truck, we glue the elements together directly on site,” explains Hoentjen. Not only can the brand acrylic glass be joined invisibly, it can also be shaped without losing any of its excellent properties. Even when curved, the product provides a distortion-free view.

Two construction phases, one pool

After final planning, the construction of a “normal pool” consists of two phases: processing the brand acrylic glass in manufacturing and the installation of the construction on site. Both tasks usually take a week to complete. “The requirements vary from pool to pool, which is what makes each project exciting,” says Hoentjen. Underwater Windows recently completed two huge, s-shaped pools arranged across two levels in Albir in Spain. “This was our greatest challenge to date, as the pools are very long and basically all panes had to be slightly curved,” says Hoentjen. “We are already working on our next project, the world’s largest pool.”

The only information he gives away is that more than 35,000 kg of PLEXIGLAS® will be used in this project.

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