USP Location, location, location. The Sheraton Iguazú is situated deep within the forested national park that is home to South America’s most impressive falls. From the bedrooms on one side of the hotel – and from the swimming pool directly outside the spa on the ground floor – the cascading water is visible through the trees.

This is a stunning place to watch the sun go down (although from the outside, the hotel itself is a monstrosity), and the Sheraton’s proximity to the waterfalls means you can explore them at close quarters before the crowds arrive in the morning.

Spa-goers who want to commune with this beautiful natural environment can opt for open-air treatments or products based on local herbs or mud.

AMBIENCE Quiet. Most guests stay at the Sheraton for just one night, said spa manager Leonardo Pascutto. With the show-stopping falls taking most of their attention during these whirlwind trips, the spa, which has been open for only two years, is almost deserted until late afternoon.

This means that those who have a little more time to linger in the area or can drag themselves indoors for an hour or two can expect to be waited on hand-and-foot within elegant and peaceful surroundings. There is an emphasis on romance, with a private Jaccuzzi for two and couples’ massages on offer.

For those who are feeling less loved-up, there is a well-equipped gym and a hydrotherapy whirlpool.

EXPERIENCE After lounging alone in the single-sex sauna for a few minutes, I opted for the Cataratas Relax (cataratas being the Spanish word for waterfalls), a 75-minute body treatment that involved being coated from head to toe in the deep red clay of the Misiones region.

The day had been a stormy one in Iguazú, and having been caught in a downpour I had already spent several hours coated in very similar mud while roaming the national park. Nevertheless, the treatment was luxuriant, with an exfoliating scrub to start after which I was slathered in the red stuff and wrapped in white sheets and towels.

Sandra, my knowledgeable if somewhat brisk therapist, explained that the clay was rich in iron and would do wonders for my pores. Because the skin on my face is a little dry, she added some moisturiser to the clay before smothering it onto my cheeks and forehead.

Then I was left alone for half an hour, and the simply-furnished treatment room was relaxing enough that I managed to doze off. By the time it came to hop in the shower and scrub – Misiones mud is harder to remove than it is to apply – my skin was silky smooth.

On a less damp day, the ‘Jungle Energetic’ massage - which takes place in a white tent in the clearing outside the spa - would have also been a must.

PRODUCTS The spa uses its own, regionally sourced and hand-made products for many of its treatments. Ingredients apart from mud include local honey and herbs such as yerba mate (apparently good for cellulite). An after-sun treatment makes use of tropical fruits and aloe vera, while the intriguing ‘chocotherapy’, involves cocoa.

IN-CROWD Travellers from the four corners of the globe - deep pockets are the only real common characteristic among the clientele. The spa itself was child-free, but families as well as couples lounged around the outdoor pool.

FOOD Herbal teas are provided free of charge as you relax after a treatment in the spa. A breakfast buffet that ranges from fresh fruit to toasted sandwiches is included in the hotel room rate.

For dinner, the restaurant has an a la carte menu, but the extensive buffet (around £15) including numerous salads, delicious (if petite) Argentinian steaks and super-creamy deserts is better value for those who are happy to take a break from calorie-counting.

WALLET WATCH Situated within spitting distance of a world-famous tourist destination, this is not a place with Argentinian wallets in mind. The Catararas Relax treatment cost £60 – a lot of money in a country where decent wine can be bought for £2 although not expensive compared with UK prices.

The Jungle Energetic massage costs around £40, while facials start at £25. A double room at the Sheraton Iguazú starts at £106 plus taxes per night (£133 with a waterfalls view), and flights from London to Buenos Aires with British Aires cost from £847. From Buenos Aires to Puerto Iguazú is a short internal flight (prices vary, see www.aerolineas.com.ar)