A wearable computing device for wearing on a head of a user, the device comprising: a waterproof storage volume configured to secure to a connector; at least two sensors secured to or within the waterproof storage volume configured to generate sensor data for motion of the user head, the at least two sensors comprising an accelerometer and a gyroscope, the sensor data comprising acceleration data and angular velocity data for the motion of the user head; a power supply within the waterproof storage volume; a wireless transceiver within or secured to the waterproof storage volume for wireless communication with at least one external device; at least one data processor secured within the waterproof storage volume coupled to at least one user output component, and coupled to at least one non-transitory computer readable medium containing processing instructions that when executed by the at least one data processor, cause the at least one data processor to: calculate a plurality of performance metrics based at least partly on the sensor data comprising the acceleration data and the angular velocity data for the motion of the user head, the performance metrics comprising an oscillating signal profile for the acceleration data and angular velocity data associated with the motion of the user head, the oscillating signal profile representing a data pattern based on data output about an axis of one of the at least two sensors during a swimming stroke as the user swims through the water; and determine a plurality of swimming stroke events based on the oscillating signal profile associated with the motion of the user head. a waterproof storage volume configured to secure to a connector; at least two sensors secured to or within the waterproof storage volume configured to generate sensor data for motion of the user head, the at least two sensors comprising an accelerometer and a gyroscope, the sensor data comprising acceleration data and angular velocity data for the motion of the user head; a power supply within the waterproof storage volume; a wireless transceiver within or secured to the waterproof storage volume for wireless communication with at least one external device; at least one data processor secured within the waterproof storage volume coupled to at least one user output component, and coupled to at least one non-transitory computer readable medium containing processing instructions that when executed by the at least one data processor, cause the at least one data processor to: calculate a plurality of performance metrics based at least partly on the sensor data comprising the acceleration data and the angular velocity data for the motion of the user head, the performance metrics comprising an oscillating signal profile for the acceleration data and angular velocity data associated with the motion of the user head, the oscillating signal profile representing a data pattern based on data output about an axis of one of the at least two sensors during a swimming stroke as the user swims through the water; and determine a plurality of swimming stroke events based on the oscillating signal profile associated with the motion of the user head. calculate a plurality of performance metrics based at least partly on the sensor data comprising the acceleration data and the angular velocity data for the motion of the user head, the performance metrics comprising an oscillating signal profile for the acceleration data and angular velocity data associated with the motion of the user head, the oscillating signal profile representing a data pattern based on data output about an axis of one of the at least two sensors during a swimming stroke as the user swims through the water; and determine a plurality of swimming stroke events based on the oscillating signal profile associated with the motion of the user head.