If your bud is drowning in a river: First, check the scene to be sure that it's safe to attempt a rescue. Check the victim, then send someone to get help and call 9-1-1, then care for the person until help arrives.
In the event of drowning, first remove the victim from the water. Check for consciousness and for breathing. If the victim is not breathing, do not waste time trying to remove water from the victim's lungs. Quickly remove any obstructions such as seaweed or excess mud from the victim's mouth, and open the airway and apply mouth-to-mouth recuscitation.
If breaths do not do in, re-tilt the head and attempt rescue breathing again. If air still does not go in, give children and adults abdominal thrusts using the Heimlich maneuver to clear the airway. Once the airway is clear, begin mouth-to-mouth and chest compression as necessary.
Hypothermia is the result of body temperatures falling below 35 C (95 F). The casualty will show signs of shivering and slurred speech, then confusion, irrationality, sleepiness, clumsiness, and shivering may stop. Babies may exhibit drowsiness and floppiness, and the face, hands, and feet will feel very cold.
Hypothermia victims should be gradually rewarmed by a warm bath and hot drinks. These are much preferable to a mere hot water bottle or electric blanket. If there are no other means of warmth, body heat can be used to warm the victim. The casualty should move to improve circulation, especially moving the legs, but the skin should not be rubbed.