In France, where he lives and works, Sjaak van Rhijn feels connected with the natural environment. This is reflected especially in the works on the water theme. For example, there are many smaller fast-flowing rivers in the area where the water flows through the rocks, there is conflict and the constantly changing shapes compete to become the basis of various statues and reliefs. Thus arose the pictures Frozen River and Rivière La Roche 1 and 2 in 2004, with the latter image in slate where the movement of the water appears.

These images are the opportunity to use transparent materials. Plexiglas as material for the movement and changing forms of water, light and its refraction.

The sculpture in which transparent plexiglass was used for the first time is entitled River Prints. These are prints of the water moving below the surface of the stone and appearing just above the stone.

This modern material is not entirely new in the work of Van Rhijn. He has extended himself in previous works to experiment as in the 70s. This has led to the spiral statues, and some small sculptures in which he used plexiglass in 1971 when he received the art award of the city of Gouda.

The new material also brings the element of colour to the workplace. This is in a special way reflected in the reliefs of the material; an almost fluorescent expression created by the incisions carried out in the reliefs made.

The reliefs are composed of layers creating extra dimensions. The light from outside and the light spots are creating images in the background. The reliefs of plexiglass are both "image" and "slide" at the same time. This is in harmony with the work he has presented in the project “Empty Locations” in 1995 in Gouda. Van Rhijn used plastic bags of debris for slides, which were projected onto the surface of a large piece of slate.

A new element in the work of van Rhijn is the human figure. An Aquarius or woman seems to go with the flow and sometimes to go against the flow and at other times to be just water.