Two dress codes meet on Saudi Arabia's Red Sea coast, and a good wardrobe holds both. Inside the new resorts between Umluj and Al Wajh, where an airport of its own now receives flights from Riyadh and Jeddah, swimwear at the pool and the beach is the norm. Beyond the resort gates, in towns, at the airport and on the road, visitors are expected to dress modestly, with shoulders and knees covered for men and women alike; foreign women are not required to wear an abaya. On the Red Sea, what to wear has to move cleanly between those two, and linen does it with very little luggage.

The destination itself is still young. The St. Regis Red Sea Resort sits on an island in the lagoon, Nujuma, a Ritz-Carlton Reserve, on another, and Six Senses Southern Dunes lies inland among the sand, so a single stay can include a boat or seaplane transfer, a reef day and an evening in the desert. October is still hot here, with days that can sit in the mid thirties and sea temperatures that stay warm well into the evening. The air on the coast is humid; in the dunes it is drier, and nights there cool noticeably.

The transfer is the first test, and it falls under the public code. Men arrive comfortably in a Laos Long Sleeve Linen Shirt in Beige Cream with PP Casual Linen Trousers in Vanille: covered, light and easy through the flight. Women do the same in the PP linen blouse in Orchid, with ankle-length trousers. Both outfits hold through the airport, the jetty and the first lunch, and neither needs changing before check-in.

Inside the resort, the wardrobe opens up. The reef that fringes the islands is the reason many people come, and for the reef, PP natural swim shorts go in: Black or Oyster read well against pale sand, and the cloth is 100% Belgian linen. Between swims, at the beach restaurant or on the walk back along the boardwalk, a Cuba Linen Shirt in Blue and PP linen shorts in White are enough. For her, the Linen Ladies Set in Mint Green, a blouse with matching shorts, covers the long middle of the day, and the Amelia linen dress shirt in Coral Orange or Hibiscus suits lunch at the island villas. Inside the resorts, where the thigh-length cut is in keeping, it is one of the easiest garments she can pack.

The desert evening is a different room. At Southern Dunes the sand gives up its heat quickly after sunset, and a short-sleeved shirt that was right at five o'clock can feel thin by nine. A Bliss Linen Shirt in Grey, long-sleeved, and the PP Trousers 100% Linen in White carry a dinner outside under the stars; women can return to the blouse, which reads as evening wear in Orchid or Lemon, with a fine knit to hand if the wind picks up. Closed shoes are kinder on cooling sand than sandals.

Many visitors add a few days inland. The tombs of Hegra and the old town of AlUla are a short flight away, and the code there is the public one throughout; our guide to what to wear in AlUla covers the canyon days in detail. For a wider view of the country, from Riyadh's majlis to Jeddah's old quarter, what to wear in Saudi Arabia is the place to start. In both, the long-sleeved shirts and the long trousers from the coast do the work again.

Much of this coast is being developed with a planned limit on visitor numbers, and the quiet of the lagoon is part of the plan.

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