Elgin County OPP responded to an urgent call on Sunday after two swimmers were reported in distress at Port Burwell beach.
One of the swimmers was rescued and transported to the hospital with non-life-threatening injuries, while the second individual failed to resurface.
Authorities closed Port Burwell Beach until further notice as search efforts continue.
Members of the Elgin County OPP, alongside the Joint Rescue Coordination Centre (JRCC) Trenton, are leading the recovery efforts.
An investigation is ongoing, and Elgin OPP can be contacted at 1-888-310-1122.
Members of the public can also contact Crime Stoppers anonymously at 1-800-222-8477 (TIPS) for a potential cash reward of up to $2,000.