Despite living on an island, the people of Galar are loath to cross its coastline and rivers on the backs of their water pokemon, instead taking to specialized bikes – for they know that Chewtle lurk just beneath the surface, ready to bite onto anything organic. Chewtle are not quite big enough to kill water pokemon of sufficient size to carry a rider, but their sharp teeth can create serious puncture wounds, and their powerful grip often tears a fin, flipper, or leg away from its owner. Although Chewtle rarely prove fatal to humans or domestic pokemon, the body parts they snack on are the very ones required for successful aquatic navigation; all one can do after a Chewtle bite is paddle desperately to the nearest shore.
If you are bit by a Chewtle, parents tell their more adventurous children, never try to free yourself. Chewtle do not let go on their own, but removing their grip is a simple procedure that can be performed at any hospital or pokemon center, involving a specialized tap on the cheeks and the back of the horn and bribing them with fish more appetizing than their current, oversized prey. Do not, under any circumstances struggle; their grip can not wrest away limbs, unless combined with your own power pulling in the opposite direction.
It has long been known that Chewtle do not bite boats, but commercial ships are too large for many of Galar's streams and rivers, and too expensive to meet a premodern farmer's transportation needs. As for smaller boats, although Chewtle are carnivores, they are known to mistake oars for food. It is no exaggeration that the invention of the Rotom bike meant a transportation revolution in Galar; a revolution lost on visitors, for whom travel over water was always normal.