Swim

Action	DC
Swimming in calm clean water	2
Swimming in a slow river	5
Swimming in mildly turbulent water (Small waves)	12
Swimming in a swiftly moving river	25
Swimming at the base of a waterfall	40
Aggravating factor	DC Modifier
Swimming against the current	+5
Cold Water	+3
Frigid Water	+10

Swimming is a basic skill that most creatures can do untrained. DCs will be set by the DM but there are some standard DCs that can be used as a basis. Creatures swim at half of their standard speed. If a creature has a swim speed, they automatically act as if they have a 15 as their roll. If the DC is higher than that, then the creature will have to roll.