General: The river will grapple your kayak & pull it 30ft downstream if neither occupant succeeds on a dc12 STR Athletics or DEX Acrobatics in a round. Success allows you to move up to 30ft to a spot of your choice, or stay still. Moving past, leaving, or crashing into the Hazards activates them (usually in the form of OAs, but some of them have their own attacks on their own "turns".
Hazard #1: Another Big Drop. The boat plunges nearly 10ft into the river and bobs back up. Instead of being pulled by the river, you wind up held in place by it. Same checks as general (dc12 STR/DEX), but failure will result in being "restrained" by the river (and possibly capsized).
Hazard #2: Sharp Rocks. You can move past it (but not through it), but you must fend it off with an attack (or it will get an OA) & try to end your turn 10ft+ away from it. One successful attack allows a kayak to "disengage" from it.
Hazard #3: Large Rocks. It's a bigger, more dangerous version of the Sharp Rocks. You can move past (but not through), but you must fend it off with an attack (or it will get an OA) & try to end your turn 10ft+ away from it. One successful attack allows a kayak to "disengage" from it.
Hazard #4: Swift Current. Unfortunately, this area also has 10ft-reach pulling effect that is bigger than the usual "30ft downstream if you fail to control your movement". There is a chance of capsizing if it gets you.
Hazard #5: Grounding. The kayak will grind on shallow stones. While moving past or away from this hazard, the kayak will take damage & halt its movement if you don't attack with paddles. As usual, 1 successful attack will neutralize the danger & you can carry on.
Familiars: A dc12 WIS Perception or INT Investigation check (AKA the "Search" Action) will allow them to warn their "master" of an upcoming Hazard, granting that PC Advantage on their Attack or Check against that Hazard.
