Yes, they do exist—though the slant is often subtle. Many outdoor benches are not completely flat. Some have a slight slope from the back edge toward the front edge, while others have a gentle crown in the middle so water runs off to either side. This type of design is sometimes called a self-draining bench or a drainage-sloped seat. The pitch is usually mild, often around 1 to 3 degrees, which is enough to move rainwater off the surface without making you feel like you are sliding forward.
In many park benches, the drainage comes less from a visible slant and more from the gaps between slats. Benches made from metal, recycled plastic, or wood slats often have open spaces between the seat boards. Those gaps let water drain through quickly, so the seat dries faster after rain. That is one reason slatted benches are so common in wet climates, coastal parks, playgrounds, trail rest stops, and pool areas.
If you are shopping for one, look for terms like “sloped seat bench,” “self-draining park bench,” or “outdoor bench with drainage gaps.” It is also worth asking the supplier about the seat pitch, drainage channels, and whether the top surface is crowned or mildly angled. A slight slope is usually comfortable for sitting, but you should avoid any bench with a strong forward tilt that makes you feel unstable.
One thing to keep in mind is the base. A bench designed with a slanted seat should normally be installed on level ground. If the whole bench is tilted too much during installation, even a well-designed seat can become uncomfortable or collect water in the wrong spots. Also, even self-draining benches benefit from occasional cleaning, because leaves, pollen, and dirt can block drainage gaps and hold moisture against the surface.
So yes—park benches with slanted or self-draining seats are available. The slope may be hard to notice at first glance, but combined with slats or drainage channels, it really does help rainwater run off and keeps the seating area drier and more usable after wet weather.