The Form Smart Swim 2 Pros AR goggles ($300) embed a tiny computer, sensors and on‑device ML to track strokes, heart rate (temples via strap retainer), guided workouts and real‑time AI coaching; models were trained from paired video/sensor datasets across hundreds of thousands of swims. Optical fixes (ultrasonic micron air pockets) stop underwater ghosting and the device claims ~14‑hour battery life and race legality.