This would be a pool where the water level in the pool is the same as the top of the decking. Around the pool perimeter is a channel or notch that the water drains into creating a visual masterpiece. It looks like a big mirror lying on the ground. The water’s surface looks like a flat sheet of glass or appears to be perfectly contained without walls.
This effect is created by a perimeter overflow, a style used in many modern swimming pool designs in which the water overflows its edges and flows into a hidden slot or catch basin where it is then recycled back into the pool. This function is similar to an infinity-edge pool, but with a perimeter overflow, the water overflows on all four sides.