Does Saturn have volcanoes craters or canyons

Saturn doesn't have impact or volcanic craters as far as we know. Saturn is what is considered a gas giant, just like its neighbor, Jupiter. Because Saturn is almost entirely fluid, any impact would be like dropping a rock in water. The fluid would wave around but settle with no sign of an impact.

The center of Saturn, which is most likely solid, would be under such immense pressure that it would be forced to remain near perfectly round, even after the rock of a meteor finally made it down that far. And that's if it could. (It probably wouldn't.) We know what earth's atmosphere does to falling rocks, and Saturn is much more massive and has a lot of atmosphere. A falling rock would have to be large to have a chance of getting to the core of the planet. The hydrogen we suspect is present in large quantities in the lower atmosphere would be compressed to much that it would become metallic hydrogen. It would be extremely hard for a rock to fall thourgh something like that.

Recall what happened to Jupiter when the comet Shoemaker-Levy struck. There were dramatic pictures of the "damage" to the atmosphere caused by the chunks of debris falling into the grasp of the Jovian gravity well. But you can bet your bottom dollar that there was no "permanent" damage. Saturn would have had largely the same effect on the space rock. Massive gravity would have torn it apart when it got close, then the atmosphere would have burned it up

Use the link below to see a cutaway view of what we think things on Saturn are like.