Regular physical activities such as walking, running, cycling, swimming, exercising and others are very important for human health. Today, such physical activities have become one of the priorities of both individuals and public administrations within the scope of preventive medicine. The measurement of many parameters related to the physical activities of people, athletes, sports scientists and coaches is very important for performance analysis and management, training planning and program optimization, reliable monitoring of health and performance goals and implementation of correct exercise practices. Typically, Global Navigation Satellite System (GNSS) and other sensors (including altimeter, compass, gyroscope, accelerometer, thermometer, and so on) in smartwatches are used to obtain mainly position, altitude/height, total distance travelled, instantaneous/average/min-max speeds, distance travelled at different speed ranges, pace, frequency/intensity of acceleration/deceleration, pauses, direction, number of steps, biological information, pulse/heart rate, respiration rate, amount of stress, sleep rhythm and hydration and others. The accuracy and reliability of the information provided by GNSS and other sensors on the smart devices is of paramount importance and, in some cases, even vital, to the users. In this study, the positioning accuracy of an embedded GNSS receiver in the Garmin Fenix 7X Solar Sapphire smartwatch has been tested with realistic field measurements under different satellite configurations and different conditions.