Abstract: A drowning or asphyxiation prevention system and methods are set forth, for facilitating drowning prevention of swimmers in bodies of water, such as pools, lakes or the like. The drowning prevention safety system comprises a wearable article worn by a swimmer, an alarm indicator for transmitting an alarm condition. The system may further include an alarm receiving system for receiving the alarm signal from the alarm transmitting device. The invention also relates to a heart rate monitoring system comprising a patch type portion to be adhesively applied to the skin of a user to monitor the electrical activity of the heart and generate heart rate information that is communicated to a separate wearable device, such as a wrist worn device.