What to Wear & Not Wear Under Swim Trunks ?

Nowadays there is no shortage of styles when it comes to swimwear- whether it be for men or women. However, today, in this article, we want to look specifically at men’s swimwear. We want to dive into that age-old question regarding men’s swimwear, and specifically swim shorts: “what does one wear under swim trunks?”.  

The range of options here includes everything from going “commando” (i.e. nude/wear nothing, au natural) to wearing a garment specifically designed to be worn under them, and everything in between- including everyday underwear (though, underwear is not an advisable option –more on that later). Ultimately, it depends on one’s preference. However, the type/style of swim shorts will certainly persuade and/or dictate what one wears (or doesn’t wear) underneath them as well.

With that said, there are many different types of swimwear/swim shorts for men out there these days. So, let’s quickly define some of the most common styles for the sake of clarity (and reference) throughout the article. But, first, let’s clarify that the term “swim shorts” throughout the article will encompass/refer to all of the most common styles listed. 

The most common swim shorts for men include:

1- Swim Trunks

Swim trunks are the most classic in the United States.  They tend to be cut like traditional shorts and are meant to be worn casually poolside/at BBQs (out of the water) as well as in the water. Also, swim trunks typically have a mesh/netted or polyester liner (though some do not). 

2- Board Shorts 

Board shorts were designed as an alternative to swim trunks for surfers. They come down longer (right at the knees or just below), and, therefore, offer greater protection. They typically do not have a liner of any kind. 

3- Square-Cut Shorts

Square Cut Shorts are a slimmer, more snuggly fitted version of swim trunks. They tend to be more popular amongst European men. 

4- Jammers

Jammers are a knee-length, form-fitting men’s swimsuit used by competitive swimmers/water-sport athletes because they help to reduce drag.  These form-fitting compression suits are very similar to cycling bottoms (basically the same thing- just without the padded crotch/buttock area) and actual compression shorts.

5- Speedo

A speedo, often referred to (in slang) as a “banana hammock”, is a small, tight swim garment for men. Its technical style name is swim briefs/swim underwear (Speedo is the trademark/brand name versus the actual style name). 

If one has chosen a pair of swim shorts that has a liner, there really is no need for additional layers underneath. So, in this case, going “commando” is perfectly okay and acceptable. However, sometimes one’s chosen swim shorts will not have a liner or the existing liner is uncomfortable; so, they will want an alternative that they can wear underneath to provide support, comfort, and/or additional coverage. 

While some may [want to] opt for their regular, everyday underwear because it is conveniently already on hand and saves money, this is not recommended. Most everyday underwear is made of cotton,  and cotton and water do not get along well over prolonged periods of time- the fabric itself does not hold up well and ultimately it will absorb water which can become uncomfortable.

Additionally, this absorption of water will weigh one down and make it more difficult to swim. 

There are several other options that one can wear underneath their swim apparel. Those options include compression shorts and other garments specifically designed for this purpose. We will be touching on some of those options in this article in addition to a few other common questions regarding men’s swim shorts- most specifically swim trunks. (Source A) (Source B)  

Can You Wear Compression Shorts Under Swim Trunks? Do You Wear Anything at All Under Them?  

As you read in the intro, there are several different styles of swim shorts for men. Some of which have a mesh/netted or polyester liner for support, comfort, and/or additional coverage; some of which have no liner.  

If you opt for a pair of swim shorts that have a liner (we’ll discuss liners more later in this article, but for now…), there is no need to wear anything else underneath them.  However, many options on the market today do not offer a liner; and, while some may like these newer styles, they still want some support, comfort, and/or added coverage underneath. So, what is one to do in this predicament? 

First, let’s be clear- whether or not your chosen pair of swim shorts have a liner, one could certainly go “commando” if they are comfortable doing so. However, if you are not comfortable and/or would prefer some support/comfort/additional coverage, you could opt for something such as swim briefs or compression shorts.  If you are looking for a complete solution then check out our recommended American Trends Swim Trunks with Compression Liner (Amazon link)

While your everyday underwear- boxers or briefs- may seem like a good, inexpensive option, it is not the best option.

As was mentioned in the intro, cotton and water do not get along well over prolonged periods of time. And, your normal boxers/briefs are typically made of cotton or some type of cotton blend. So, they may be ok if you intend to stay on land and dry. However, if you intend to be in the water and/or on getting wet, your everyday underwear is not an advisable choice. 

Additionally, the cotton will absorb water. That super-saturated fabric then sits directly against your skin, and, in turn, can cause chafing/irritation (which can be sore/painful). Also, this absorption of water will add weight which will ultimately make swimming more taxing. 

Instead, one wants to opt for something made of moisture-wicking material such as compression shorts, surf undershorts, or swim briefs/underwear (also known as a ”banana hammock”/ Speedo).  From a cost perspective all of these options are in the same neighborhood; so, while one’s exact budget will certainly be a factor,  ultimately, it will be a matter of which option one finds most comfortable. 

In general, as we’ve mentioned, if your swim shorts have a liner, there is no need to wear any additional layers underneath. However, if one’s swim shorts do not have a liner and they would like some support/comfort/additional coverage, the choice is theirs- just remember it’s best to stay away from everyday underwear/cotton material; stick to garments made of moisture-wicking material. (Source A) (Source B)

Do Swim Trunks Have Liners? Can You Cut the Mesh Lining in Swim Trunks [out]? 

We have sufficiently established that some men’s swim shorts, such as swim trunks typically have a mesh/netted or polyester liner while others, such as the board short, typically do not have a liner. 

Liners- whether mesh/netted or polyester- fit snuggly and can help provide support, comfort, and/or additional coverage; however, some would counter that the liner serves no real purpose and the cons of them outweigh the pros.  

The pros are the aforementioned support, comfort, and/or additional coverage. The cons include groin discomfort from it fitting too tight, or chafing/irritation which can also be sore/painful (as was previously mentioned). 

Personally, while I’m not a male, and therefore, cannot attest to any of the aforementioned pros and cons from personal experience, the cons are all logical, possible, and thereby, plausible. And, I, therefore, would have to agree that the cons outweigh the pros.  So, then what can one do? Can one just cut the liner out? 

YES! It is absolutely possible to cut out the mesh/netted or polyester lining of your swim trunks. You just have to be careful not to cut the swim trunks themselves or the seam stitching- either situation could be problematic/ruin the swim trunks

Once the lining has been cut out, it will depend on personal preference as to what one wears underneath. Some prefer to do without any additional layers and are comfortable au natural; so, they go “commando”- and, this is completely acceptable. However, if you are not so comfortable au natural and/or just prefer support, comfort, and/or additional coverage, one could opt for a garment made of moisture-wicking material such as compression shorts, jammers, surf undershorts, or swim briefs. (Source A) (Source B)

Do You Wear Swim Trunks Under a Wetsuit? 

What to wear under a wetsuit is most likely one of the most common questions from those that are new to water sports requiring them to wear one (at least at some point, even if not regularly).  There are several options from nothing at all to specially designed garments.

Whether one wears swim trunks, board shorts,  a bikini/swimsuit, or nothing at all under their wetsuit is a matter of personal preference. However, most prefer to wear a swimsuit/bikini  (females) or board shorts (males). And, some may need sport-specific gear depending on their particular water-based activity. 

Wetsuits are designed to keep one warm and protected without having to wear anything special underneath. However, here are some general guidelines: 

  1. Surfers/General water: most opt for board shorts (males) or a swimsuit (females). To avoid bunching, males may opt for rash undershorts, jammers, or swim briefs versus board shorts. 
  2. Triathletes: those swimming in open water will typically opt to wear swim briefs (males) or a swimsuit (female) underneath. Those that are competing (versus just practicing) will often wear bike shorts (females will often opt for a sports bra with the bike shorts), a one-piece tri-suit (males/females), or jammers (swimsuit for females). 
  3. SCUBA Diving: most will simply wear a swimsuit or trunks under their wetsuit. If one is cold water diving they may opt for a full-body rash guard or a poly-fleece baselayer underneath their wetsuit for added warmth and protection. 

As was just mentioned, wetsuits are designed to keep one warm and protected without additional layers; so, I’d be remiss if I didn’t mention this- keep in mind that wetsuits work by letting water inside and trapping it there. The trapped water is heated by your body, and the heated water in turn keeps your body insulated against the cold. So by wearing additional layers under the wetsuit, the water has barriers between it and your skin, thus taking longer to heat up. 

However, on the flip side of that, while one can go certainly go “commando”, one wants to keep in mind the potential for chaffing/irritation, their destination (i.e. where are you going to swim), and their (that destination’s) rules/regulations, and modesty for in the event you need a break from your wetsuit/have to change publicly. 

So ultimately, one does need to wear anything under their wetsuit unless

1. they are renting a wetsuit (obvious hygienic reasons here) or

2. You will need to change in public (most places frown upon public nudity of any kind).

However, if you prefer to have an additional layer/barrier to prevent chafing or irritation, it’s pretty safe to go with swim briefs/jammers (males) or a one-piece swimsuit/Sports Bra style top and diving shorts (females). (Source A)

Can Girls Wear Guys’ Swim Trunks? 

Girls can wear guys’ swim shorts (most specifically and typically seen, the board short). Board shorts were designed as an alternative to swim trunks for surfers. They are longer than swim trunks, coming right to or below the knee. This longer length offers more protection from the water and sun. When board shorts first became popular, they weren’t designed for/ there weren’t any styles specifically for women. 

Yet, some women wanted that same protection from the sun and water while they too surfed (versus wearing a bikini and/or rash guard top with a bikini bottom). Some women just liked the idea of something less revealing than what used to primarily be on the market for females (i.e. not every female wants to be scantily clad while around/in the water). So, since they didn’t have such a design/style specifically for women at the time, women started wearing men’s swim shorts- be it trunks, board shorts, or square-cut shorts. 

Nowadays, women’s styles have evolved and offer many shorts and/or less revealing options for women that are specifically designed for the female body shape. So, many women these days will opt for one of these styles as it is a bit more flattering to the female body shape yet keeps them modest. However, some females have found that the square-cut shorts are a good casual short option for the warmer spring and summer months- they are that perfect length between short shorts and Bermuda-style shorts (again, flattering to the female body shape while maintaining modesty). 

So nowadays it’s probably 50/50 as to whether girls (women) opt to wear male-style swim shorts or female-style swim shorts. But, regardless, it is acceptable for girls (women) to wear men’s swim shorts- even today still. 

When looking for shorts suited for being in and out of the water, female surfers will typically want a shorter swim/board short – somewhere close to 5 inches. Females that will be kayaking, paddle boarding, and/or just prefer additional coverage can opt for longer swim/board shorts – somewhere between 7 and 9 inches. (Source A) (Source B)

Melissa Frank

My passion, outside of animals, is helping people and adding value to their lives…I strive to leave the world a little better than I woke to it each day. The first part of my career, for a total of about 15 years, was spent in the public safety field as a Volunteer Firefighter/EMT-B and 9-1-1 Operator. In 2019 I obtained my personal trainer certification (ACE certified) as well as many group fitness certifications and certification as a Corrective Exercise Specialist.

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