The Truth About Sweating While Swimming and the Importance of Hydration

Sweating is one of the clearest signs of a tough workout but what about when you’re swimming? Since you’re surrounded by water, it’s easy to assume you’re not sweating at all. But in reality, your body still produces sweat while you swim, and staying hydrated is just as important as it is for any land-based workout.

Do You Sweat While You Swim?

The short answer: yes.

"It's a common misconception that you don't need hydration when swimming because you don’t feel yourself sweating," says Marni Sumbal, RDN, an exercise physiologist and triathlon coach. "You may not feel sweaty because the water is cooling you down, but that doesn’t mean you aren’t sweating."

A Journal of Science and Medicine in Sport study found that elite swimmers lost an average of 6.8 fluid ounces of sweat per mile swum almost a full cup every 20 minutes. And while sweat rates vary from person to person, most swimmers experience some level of fluid loss.

How to Tell If You’re Sweating in the Pool

Since sweat blends seamlessly into the water, it’s harder to notice than during a land workout. But there are a few subtle signs:

• Heavy breathing or feeling winded: An elevated heart rate often signals sweating.

• Feeling warmer in the water: If the pool felt cool when you first got in but now seems warmer, it’s a sign that your body temperature has risen likely causing sweat production.

• Post-swim dizziness or fatigue: These could be signs of dehydration, which can occur when you lose fluids without realizing it.

Do You Sweat As Much in Water As on Land?

Even though the pool keeps you cool, your body still sweats to regulate temperature. "You probably sweat as much in water as you would on land, but the pool’s temperature makes it feel less noticeable," Sumbal explains.

This means hydration is just as important for swimmers as it is for runners, cyclists, or gym-goers.

Why Hydration Matters for Swimmers

If you’re not hydrating properly while swimming, you may be short-changing your workout and increasing your risk of discomfort or dizziness afterward.

• Muscle function and cramp prevention: Blood is primarily made of water, and staying hydrated ensures optimal muscle performance and reduces the risk of cramping.

• Avoiding post-swim dizziness: Some swimmers experience orthostatic hypotension, a drop in blood pressure when transitioning from a horizontal to a vertical position. Dehydration can make this worse, leading to lightheadedness when you stand up after swimming.

• Better endurance and focus: Symptoms of dehydration fatigue, headaches, and difficulty concentrating can affect your swim performance and overall well-being.

If you’re unsure whether you’re drinking enough, check your urine color after your workout. If it’s darker than a light yellow, you may need to hydrate more.

The Best Way to Stay Hydrated While Swimming

A solid hydration plan starts before you even get in the water and continues throughout your workout.

• Pre-swim: Drink a glass of water at least 20 minutes before getting in the pool.

• During your workout: Keep a water bottle at the end of the lane and sip between intervals at least every 10 minutes. Consider adding an electrolyte tablet or powder to replenish lost minerals.

• Post-swim: Drink another glass of water within 10 to 20 minutes after finishing your workout to replenish fluids.

Even though swimming might not make you feel as sweaty as running or cycling, your body still loses fluids. Staying hydrated will help you perform at your best and recover more effectively.

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