A wetsuit may not be necessary if the water temperature at your surfing location is around 65°F (18°C) or above. But many surfers prefer to wear a wetsuit or black suit—even in warm water—as the body can still feel chilly after a while, especially during technical or deep scuba diving.

Whether a wetsuit is "necessary" depends primarily on water temperature, duration of activity, and safety. Most experts agree that if the water temperature is below 18°C (65°F), a wetsuit is essential to prevent hypothermia and keep your muscles loose for swimming or surfing. In water between 18°C and 21°C, it is highly recommended for sessions lasting longer than 30 minutes. Beyond thermal protection, a wetsuit is often necessary for safety and buoyancy; the neoprene material provides extra lift, which is vital for beginners or open-water swimmers in rough conditions. It also serves as a protective barrier against external hazards like jellyfish stings, reef cuts, and severe sunburn. In certain competitive events, such as Ironman triathlons, wetsuits are legally "mandatory" if the water temperature falls below a specific threshold (usually 16°C) to ensure the safety of all participants. While you can certainly go "bare" in tropical waters above 22°C, even then, a thin "rash guard" or shorty wetsuit is often advised to prevent skin abrasions from surfboard wax or the elements during extended periods of play.