Half Distance Triathlon Coeur d'Alene, Idaho - Course Overview Compete in the stunning Half Distance Triathlon in Coeur d'Alene, Idaho, where athletes experience a 1.2-mile swim in the crystal-clear waters of Lake Coeur d’Alene. This iconic 50-square-mile freshwater lake, located in Northern Idaho, offers a swim course with average water temperatures of 68°F (20°C). The swim route takes participants in a counter-clockwise direction, starting south and returning north, leading to a centralized ...