Can You Swim in Regular Shorts? Cotton, Running Shorts, and Swim Trunks Compared

TL;DR: You can swim in regular shorts — but you probably won't enjoy it. Cotton shorts absorb up to several times their weight in water, turning heavy and clingy the moment you get out. Running shorts handle water better but lack support, chlorine resistance, and structure once wet. Purpose-built men's quick-dry swim trunks are engineered from the ground up for water: fast-drying synthetic fabrics, built-in liners, and construction that resists salt and chlorine. If you're near water more than once a summer, the difference is night and day.

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We've all been there. You're at the beach, a pool party, or a lake house, and you didn't bring swim trunks. You look down at whatever shorts you're wearing and think: these will work, right?

Technically, yes. No pair of shorts will dissolve in water. But "technically works" and "actually comfortable" are very different things. This guide breaks down exactly what happens when you take cotton shorts, running shorts, and purpose-built swim trunks into the water — and why the differences matter far more than you'd expect.

 

Cotton Shorts: The Worst-Case Scenario

Cotton is comfortable on land. It breathes, it softens with every wash, and it's the default fabric for most casual shorts in your closet. In the water, though, cotton has one massive problem: it's essentially a sponge.

Water Absorption

Cotton fibers are hydrophilic — they actively attract and hold water. When you jump into a pool wearing cotton chinos or canvas shorts, the fabric soaks up water quickly and thoroughly. What were light, comfortable shorts a moment ago are now heavy, sagging, and plastered to your legs.

Weight When Wet

Wet cotton shorts can feel dramatically heavier than dry ones. That extra water weight pulls at your waistband, drags the hem down, and makes basic movements like climbing out of a pool noticeably harder.

Drying Time

This is where cotton really falls apart. Because the fibers trap water internally (not just on the surface), cotton shorts can take hours to air-dry in warm conditions — and even longer in humidity or shade. You're essentially wearing a damp towel for the rest of the afternoon.

Comfort

Wet cotton clings, chafes, and stays cold against your skin. There's no liner, no support, and no structure once the fabric is saturated. Walking any distance in soaked cotton shorts is a recipe for inner-thigh irritation.

Chlorine and Salt Resistance

Cotton has essentially none. Chlorine breaks down cotton fibers over time, weakening the fabric and fading color. Salt water leaves cotton stiff and crusty once it dries. A few pool or ocean sessions can visibly age a pair of cotton shorts.

The verdict: Swimming in cotton shorts is possible, but it's uncomfortable, slow to dry, and hard on the fabric. It's a one-time emergency, not a strategy.

 

Running Shorts: Better, but Not Built for Water

Running shorts seem like a smarter option. They're lightweight, often made from synthetic materials, and some even have built-in liners. Closer to swimwear, right?

Closer, but still not there.

Water Absorption

Most running shorts use lightweight polyester or nylon, which are far less absorbent than cotton. Water sits on the surface rather than soaking into the fibers, so you won't experience the same heavy, sponge-like effect. On this front, running shorts perform reasonably well.

Weight When Wet

Because they absorb less water, running shorts stay relatively light when wet. You won't feel the same waistband drag that cotton creates. So far, so good.

Drying Time

Here's where things get muddier. Running shorts dry faster than cotton, but they're still not optimized for water. The fabric weight, weave density, and construction are designed for sweat management and airflow during land-based exercise — not for shedding pool or ocean water as quickly as possible. They'll dry, but not as fast as you'd want if you're heading straight to lunch.

Comfort

Running shorts are designed for movement on land, and they're great at that. But in water, the fit can work against you. Many running shorts have very short, loose cuts with side slits that ride up and flap around when swimming. The lightweight fabric that feels great on a run can feel flimsy and unsupportive when submerged.

The Liner Problem

Some running shorts have built-in briefs or compression liners — but these are designed for a very different purpose than swim trunk liners. Running liners are typically made from dense, moisture-wicking compression fabric that holds sweat against your body for evaporative cooling. In water, that same compression fabric absorbs and holds water, creating a slow-drying, heavy layer right against your skin. It's the opposite of what you want after a swim.

Chlorine and Salt Resistance

Running shorts aren't treated or constructed to withstand repeated chlorine or salt exposure. The elastic in the waistband and liner can degrade, colors may fade, and the fabric can lose its stretch recovery over time. A summer of pool use will noticeably shorten the lifespan of most running shorts.

The verdict: Running shorts handle water better than cotton, but they're still a compromise. The liner, construction, and fabric aren't designed to go from wet to dry and back again — which is exactly what a day near water demands.

Purpose-Built Swim Trunks: Engineered for Water (and What Comes After)

Here's where things change significantly. Men's quick-dry swim trunks aren't just "shorts that can get wet." Every element — fabric, liner, stitching, waistband — is designed around a specific cycle: dry → wet → dry again, as fast as possible, with minimal discomfort in between.

Water Absorption

Swim trunk fabrics are hydrophobic by design. The synthetic yarns don't absorb water internally the way cotton does. Instead, water sits on the surface and sheds off. A tightly woven fabric amplifies this effect — finer yarns and a denser weave mean less space for water to hide between fibers, so the fabric releases moisture faster.

Weight When Wet

Because the fabric repels rather than absorbs water, quality swim trunks barely change weight when wet. You step out of the ocean, give them a quick shake, and they feel almost the same as they did on land. No sagging, no dragging at the waistband.

Drying Time

This is arguably the biggest functional gap between swim trunks and any other type of short. Purpose-built quick-dry swim trunks are engineered to go from soaked to dry in minutes rather than hours. Blauw's OceanKnit™ fabric, for example, dries in approximately 7 minutes — which means you can swim, towel off briefly, and sit down for lunch without that lingering damp feeling. Compare that to cotton shorts still dripping an hour later, and the difference becomes hard to ignore.

Comfort

The best swim trunks feel comfortable both in and out of the water. That means a fabric that's soft rather than stiff or scratchy, a fit that flatters without restricting movement, and a waistband that stays put whether you're swimming laps or sitting at a café.

The Liner Advantage

This is one of the most underrated differences. Swim trunk liners are specifically designed to drain water quickly, provide support in the water, and prevent chafing during extended wear. The best designs use ultra-fine micro-mesh — a material that lets water pass straight through and air circulate freely, so the liner dries almost as fast as the outer fabric. That's fundamentally different from a running short's compression brief, which traps and holds moisture.

Chlorine and Salt Resistance

Quality swimwear for men is constructed to withstand exactly the conditions that destroy cotton and running shorts. Salt water–resistant and chlorine-resistant construction means the fabric maintains its color, stretch, and structural integrity through an entire summer of heavy use — not just a single spontaneous dip.

 

The Quick Comparison

Feature	Cotton Shorts	Running Shorts	Swim Trunks
Water absorption	Very high	Low–moderate	Very low
Weight when wet	Significantly heavier	Slightly heavier	Minimal change
Drying time	Hours	30–60+ minutes	Minutes
Comfort in water	Poor (clingy, heavy)	Moderate (flimsy, unsupportive)	High (structured, supportive)
Chlorine/salt resistance	None	Minimal	Built-in
Built-in liner	No	Sometimes (wrong type)	Yes (designed for water)
Wearable after swimming	Not comfortably	Somewhat	Immediately

When Does It Actually Matter?

If you're jumping in a lake once on a dare, wear whatever you have on. It doesn't matter. But if you're spending any real time near water this summer — beach vacations, pool weekends, coastal travel — the gap between regular shorts and purpose-built swim trunks compounds fast.

It's not just about the swim itself. It's about the two hours after the swim. The walk back from the beach. The lunch reservation. The afternoon spent exploring a new town. Regular shorts force you to either stay wet and uncomfortable, carry a change of clothes, or skip the water entirely. The right pair of swim trunks removes that tradeoff — you swim when you feel like it, and your day continues seamlessly without a wardrobe crisis.

That's ultimately what makes investing in a proper pair worth it. Not the swim — the everything else.

Key Takeaways

• Cotton shorts are the worst option for water: they absorb heavily, take hours to dry, offer no support, and degrade quickly from chlorine and salt.
• Running shorts are better but still compromised: lighter fabric handles water okay, but the liner, construction, and durability aren't designed for repeated wet-dry cycles.
• Swim trunks are purpose-built for the full cycle: fast-drying fabric, water-draining liners, chlorine and salt resistance, and comfortable structure both in and out of the water.
• The real difference shows up after the swim: quick-dry swim trunks let you continue your day immediately, while regular shorts leave you damp and uncomfortable for hours.

 

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FAQ

Can swimming in cotton shorts ruin them?
Repeated exposure to chlorine or salt water can weaken cotton fibers, fade colors, and leave the fabric feeling stiff. A single spontaneous dip probably won't destroy them, but it's not something cotton is built to handle regularly.

Are running shorts okay for a quick swim?
For a brief, unplanned dip, running shorts are a better choice than cotton. But they lack the liner design, chlorine resistance, and fast-drying construction of swim trunks, so they're not ideal for anything more than an occasional splash.

What makes swim trunk liners different from running short liners?
Swim trunk liners — especially ultra-fine micro-mesh designs — are built to drain water instantly and dry fast. Running short liners use compression fabric designed to wick sweat, which actually holds water when submerged and dries much more slowly.

How fast do proper swim trunks dry compared to regular shorts?
It depends on the fabric and construction. High-performance swim trunks like those made with Blauw's OceanKnit™ fabric dry in approximately 7 minutes. Cotton shorts can take several hours, and running shorts usually fall somewhere in between.

Is it worth buying swim trunks if I only swim a few times a year?
If you spend any time near water — even casually — a quality pair of swim trunks doubles as versatile summer shorts you can wear every day. You're not just buying swimwear; you're buying shorts that happen to be ready for water whenever you are.