A great many Hideaway Report-recommended hotels and resorts have on-site spas and fitness centers. However, the very best offer a wealth of treatments, often with locally sourced ingredients, which pamper their fortunate guests amid serene and opulent surroundings. Here are 13 of our favorite spas in the world, places where health and wellness are paramount and indulgence is endlessly refined.

Royal Mansour

Marrakech, Morocco

Like everything at the Royal Mansour, the spa is breathtakingly beautiful and flawlessly serviced. A candlelit entry tunnel opens theatrically onto a soaring lounge centerpieced by a flower-filled marble fountain. The glass-enclosed indoor pool looks as if it were designed by Gustave Eiffel. After an hourlong hammam treatment, conducted in a private marble hall, the remainder of time can be spent sipping lemon-ginger infusions on a daybed in the relaxation lounge amid whitewashed wood screens and creamy raw-silk drapes.