Can Muslim men wear shorts on holiday?

Yes, Muslim men can wear shorts on holiday, as long as they cover the knees. A man's awrah is from the navel to the knee, so knee-length or longer shorts are fine at the beach, the pool or around town. Short shorts and tiny swimwear are not.

A man's awrah

Most scholars say a man must cover from his navel to his knees in front of anyone other than his wife. The Hanafi school counts the knee itself as part of the awrah, while the Shafi'i and Hanbali schools say the knee isn't, though covering it is safer. A minority view, found among some Maliki and Hanbali scholars, treats the thigh as a "lighter" awrah, but the main position in all four schools is that the thighs should be covered. This applies on holiday just as at home.

يَـٰبَنِىٓ ءَادَمَ قَدْ أَنزَلْنَا عَلَيْكُمْ لِبَاسًا يُوَٰرِى سَوْءَٰتِكُمْ وَرِيشًا ۖ وَلِبَاسُ ٱلتَّقْوَىٰ ذَٰلِكَ خَيْرٌ "O children of Adam, We have bestowed upon you clothing to conceal your private parts and as adornment. But the clothing of righteousness — that is best." Quran 7:26

What works in practice

Knee-length or below: board shorts, cargo shorts and three-quarter shorts that cover the knee when you sit are ideal.
Not too tight or see-through: once wet, thin fabric can cling, so pick thicker swim shorts.
Swimming: long board shorts or "jammers" work at the beach and pool. See Can I still go swimming at a public pool as a Muslim?
Tops: going shirtless isn't haram for men, but a T-shirt or rash guard is more modest and protects against sunburn.

Praying in shorts

If your shorts cover from navel to knee, your prayer is valid. Some scholars note it's better to pray in more complete clothing, since Allah says to "take your adornment" for prayer (Quran 7:31). Many brothers keep light trousers in their bag and slip them on over shorts to pray, especially in a mosque.

Visiting mosques and local culture

In many countries, including Muslim-majority ones, shorts are fine on the beach but frowned on in town, and mosques often ask men to wear long trousers. Pack at least one pair of lightweight long trousers. The same rules apply at home, for example at the gym. See Can I still wear shorts to the gym as a Muslim?

Lowering the gaze goes both ways

Modesty for men isn't only about your own clothes. Beaches and pools are where lowering your gaze matters most (Quran 24:30). Choosing quieter beaches or family-friendly resorts makes this easier. See What is halal travel?

Key points

Men cover from navel to knee, also on holiday.
Knee-length, loose shorts are fine; short shorts are not.
Use thicker swim shorts that don't cling when wet.
Bring long trousers for mosques and prayer.

Tip: When buying swim shorts, sit down in the fitting room. If the hem rides above your knee when seated, go one size longer.