Men's Swimming Trunks

Mariner Underwear men's swimming trunks are stretch swimwear in polyamide and elastane, with a polyester inner lining and an interior drawstring. Available in M, L and XL in geometric print colourways. For a tighter fit, see our men's swim briefs. For a longer option, browse our men's swim shorts.

Men's Swim Trunks: Mid-Length Swimwear

Men's swimming trunks cover the upper thigh. They are longer than swim briefs, which sit high on the thigh, and shorter than board shorts, which reach the knee. That mid-length position makes them the most widely bought cut in the UK market. They work at the pool, on the beach and on holiday without looking out of place. The brand keeps things simple: quality material and a cord that holds. A practical choice for men who want something that works without unnecessary extras.

Quick Dry Swim Shorts: Essential Fabric

The outer fabric in Mariner Underwear's swimming trunks is a stretch blend of polyamide and elastane, with a polyester inner lining. Both dry faster than cotton and resist chlorine and salt water. Stretch swimwear in this blend is ready to wear again within minutes of leaving the water. Cotton swimwear, by contrast, stays wet long after you leave the pool. This blend is common across quick-dry men's swimwear for that reason. Machine wash at 30 degrees, hang in the shade.

Inner Lining and Drawstring Waist

Every Mariner Underwear swimming trunk has a built-in polyester inner lining. It provides support in the water so no separate undergarment is needed. An interior drawstring lets you fine-tune the fit. Loosen it at the poolside, tighten it before getting in. Loosen the drawstring before machine washing to protect the lining.

Geometric Print Colourways

The Mariner Underwear trunks collection currently covers two geometric print colourways. One is navy and white, the other a blue gradient in indigo. Both are printed, stretch-fabric styles.

Swim Trunks vs Swim Brief: Holiday Beach Essentials

The three main cuts of men's swimwear each suit different needs. Swim briefs are the shortest, used by competitive swimmers who want minimum material. Swim trunks and swim shorts are mid-length. The terms are interchangeable in the UK. An essential cut for casual use in the water, at the beach or on holiday because these mid-length shorts cover enough without limiting movement. Mariner Underwear stocks both briefs and longer-length shorts alongside this mid-length range.

Sizing

Mariner Underwear men's swimming trunks are available in M, L and XL. Take your normal size. The interior drawstring lets you get the right fit. The mid-length leg sits on the upper thigh across all three sizes. Go up one size for a more relaxed cut. The inner lining sits flat without bunching.

Care Instructions

Rinse in cold clean water after each use. Chlorine and salt can degrade the fabric if left in. Machine wash at 30 degrees without fabric softener, which coats the fibres and reduces quick-dry performance. Hang to dry in the shade. Do not tumble dry. A well-maintained pair from this range will hold up through several summer seasons.

Shop the Trunks Collection

Mariner Underwear is a UK clothing brand with over 50 years in men's swimwear. The swim trunks range sits alongside men's swim shorts and briefs for a complete range of men's swimwear. The navy geometric colourway is a favourite for everyday use and a versatile option for the holiday shop or packing light. Shop both colourways above. Contact us for sizing or material questions.

Frequently Asked Questions

What length are men's swimming trunks?

Men's swimming trunks are mid-length, covering the upper thigh. They sit between swim briefs (shorter) and board shorts (longer, to the knee). The mid-length cut is the most popular for pool and beach use in the UK.

What is the difference between swimming trunks and swim shorts?

In UK usage the terms are largely interchangeable. Both refer to mid-length swimwear. Board shorts are the longer style. At Mariner Underwear, both names refer to the same mid-length range.

Do men's swimming trunks have a built-in lining?

Yes. Every Mariner Underwear pair has a polyester inner lining. It provides support in the water so no separate undergarment is needed.

Do Mariner Underwear swimming trunks have pockets?

No side or rear pockets on this range. The trunks have a stretch fit with an interior drawstring and a polyester inner lining.

How do I wash my swimming trunks?

Rinse in cold water after each use to clear chlorine or salt. Machine wash at 30 degrees without fabric softener. Dry in the shade. Loosen the drawstring before washing to protect the lining.

What fabric are Mariner Underwear swim trunks made from?

A stretch blend of polyamide and elastane, with a polyester inner lining. It dries quickly and resists chlorine and salt water.

What sizes are the swimming trunks available in?

M, L and XL. The interior drawstring lets you get the right fit. Take your standard size and go up one for a looser cut.