Much of Vieques was off limits for most of the twentieth century. The United States Navy used large parts of the island from the 1940s until it withdrew in 2003, and the land it left became the Vieques National Wildlife Refuge, which is why the island's beaches are still lined with sea grape and scrub rather than hotels. A day here means a rented jeep, a dirt road, an empty beach and a small town for dinner, and what to wear in Vieques has to tolerate dust and salt by day and look composed at a waterfront table by night.

The island lies a few miles off the east coast of the main island of Puerto Rico, reached by ferry from Ceiba or by a short flight from San Juan. It has two towns. Isabel Segunda, on the north coast, is the ferry port and the administrative centre, with a small Spanish fort, the Fortín Conde de Mirasol, on the hill above it. Esperanza, on the south coast, is a single waterfront of guesthouses, bars and restaurants facing the Caribbean. Horses wander freely across the island, along the roads and through both towns, and drivers learn to slow for them.

The beach days come first. Playa Caracas, Pata Prieta and La Chiva, on former navy land along the south coast, are reached by unpaved tracks through the refuge, and there is little shade and few facilities at most of them. PP natural swim shorts in Sapphire Blue or Oatmeal go into the sea; the PP linen shorts in Navy Blue, with a Laos Short Sleeve Linen Shirt in Coral Orange or Pink from the men's collection, are for the drive and the beach picnic. For her, the Linen Ladies Set in Sky Blue suits a day of climbing in and out of a jeep better than a dress, and the blouse half can go on over a swimsuit when the sun is high.

Esperanza at night is relaxed but not careless. The waterfront restaurants are open to the breeze, tables sit almost on the sand, and the evening dress is a clean shirt rather than a jacket. A Cuba Linen Shirt in Lemon Yellow or the Bliss Linen Shirt in Pink, with PP Casual Linen Trousers in Oatmeal, fits the mood; for her, the Amelia linen dress shirt in Hibiscus or Blue, worn as a dress with flat sandals, is enough for any table on the island.

The bioluminescent bay asks for its own outfit. Mosquito Bay, a sheltered lagoon west of Esperanza, is known for the microorganisms that light up the water when it moves, and tours go out after dark by kayak or electric boat, ideally on a night with little moon. Swimming in the bay is not permitted, so the swim shorts stay behind. What helps is a layer for the insects at dusk and something that will not mind a splash from the paddle: a Laos Long Sleeve Linen Shirt in Dark Blue, or the PP linen blouse in Sky Blue for her, with long, light trousers and shoes you can get wet. Insect repellent goes on before the shirt does.

October sits late in the Atlantic hurricane season, so travel insurance and a flexible ferry plan are worth arranging; most days are simply hot, humid and bright, with heavy showers that pass. Those flying in through San Juan often spend a night or two on the main island first. The collection itself is presented at Four Seasons Resort and Residences, Río Grande, Puerto Rico, on the way from San Juan to the Ceiba ferry, and our guide to what to wear in Puerto Rico covers the rest of the main island, from Old San Juan to the rainforest of El Yunque.

The ferry from Ceiba can fill early at weekends and on holidays; the short flight from San Juan is the surer way across when it does.

Read more: What to Wear in San Juan for Women  ·  The Best Linen Brand for Puerto Rico