Mr & Mrs Smith

Looking out through the floor-to-ceiling windows of the Scarlet Hotel, I can see a pair of wiggling legs sticking out of a giant barrel pointing up to the silver-grey sky above Mawgan Porth Bay. It's as though I've spotted someone who's fallen into a giant bowl of soup.

The legs belong to Phil – the Scarlet's Hot Tub Host. He is preparing his Dutch Kettles as he calls them, which are dotted around the cliff face, and shot with red light, glowing like unearthly cauldrons. We've just arrived and as I'm watching Phil at work, a friendly person suddenly appears by my side in the manner of Mr Benn's shopkeeper. This sleek eco hotel has dispensed with the formality of a reception desk and this kind soul is here to warmly invite us to enjoy this beautiful art gallery, restaurant and spa as if it were our own home.

These Smiths have decided to forget our real home for a couple of days in favour of this wonderfully calm and luxurious eco-hotel. As we share our actual home with two noisy children, it's a delight not to have to constantly threaten our fellow residents with a spell on the 'naughty sofa'. Apart from a notable absence of kids, The Scarlet has few – if any – house rules. Behind the scenes I imagine it is run with the quiet but firm efficiency of an Audi engine – albeit one that has been converted to run on leftover organic kitchen waste.

An ethos of sustainable comfort rather than self-conscious consumption abounds; this hip hotel could wear a line of stars on its sleeve for service and facilities. But there's no showiness here – this is the kind of place that prefers to let you uncover its special powers yourself. 'It's rather like a stealth super hero that prefers to befriend you as Clark Kent or Diana Prince then work its magic when you're not looking,' I suggest, sagely, to Mrs Smith. Not a comic book aficionado, I fear Mrs Smith has failed to grasp the gravitas of my wisdom.

Talking of new friends, everyone who works at the Scarlet is, without exception, polite and confident, super respectful of guests, each other and, of course, the environment. The Scarlet's consideration for all things natural is demonstrated by thoughtful details guaranteed to please eco-worriers such as this once professional GreenSmith. There's adjustable lighting, delicious menus based on supply rather than demand, discounts for people who come by train and taxi, unconditioned heat and air, customised furniture and sculptures made from recycled glass and paper. Guests even receive a little cloth bag for them to take home any half-used bars of soap. Take that, Cowshed.

As with all of the bedrooms, ours has an amazing view of the Cornish coastline and Mawgan Porth's golden stretch of sand and ever-shifting seascape in shades of charcoal, blue and emerald is entirely hypnotic. For a few hours after we arrive, we just lie down listening to the waves crashing beyond our window. Mrs Smith, a non-recovering TV addict, notes that such is the sensory beauty of this place the sound of television would feel an intrusion. But the Scarlet is not about prohibition, so we fling off our hairshirts and spend Saturday afternoon wallowing in a long lazy cream tea and uninterrupted DVD – luxury indeed.

In keeping with a mission statement to 'challenge the convention of other hotels', there are no tea or coffee making facilities in the room, but reviving beverages of every variety will arrive within minutes of guests picking up the phone. We take full advantage on several occasions, sampling the rose, vanilla, camomile, ginger, cinnamon and cardamom treats from the Pukka range of teas.

With surfing, kayaking, coasteering or horse riding on the beach among the outdoor pursuits on offer here, you may find small-screened distractions easily eclipsed. We head for a dip in the indoor pool, trotting up and down wooden steps past the circular bar of cosy booths above the panoramic Atlantic-view restaurant. We glide past couples all chatting and smiling, creating a constant hum of happiness over breakfast, lunch and dinner.

Even the booze at this boutique bolt hole empathises with the elements here, and at aperitif time we toast our Smith reviewing duty with a Dark and Stormy cocktail. Settled in the small but eclectic library amid Henry James, Stiegg Larsson, JD Ballard, Iris Murdoch and Spike Milligan, we leaf through the catalogue of local artists displaying their works here. Fantisising about how we might decorate our own home with specially commissioned sea-inspired landscapes by Cornwall's artistic talent, we mentally plan where pieces by Lucy Turner and Steve Yeates might fit perfectly chez Smith.

With word that Michelin-starred chef Ben Tunnicliffe likes to put a smile on diners' faces and a warm feeling in their bellies, we surrender happily to supper. By the time Mrs Smith has reluctantly eaten the last molecule of her chocolate brûlée, we are as content as can be and we succumb to that decadent tiredness in a way one only can when there's a guaranteed lie-in on the horizon.

Waking early with too much energy, I leap out of bed and start doing semi-naked press-ups on the sunny balcony. Clearly this ruins a romantic moment - and possibly breakfast - for the couple out walking below. Undeterred by my pants, Mrs Smith tucks into Arlington Eggs and then disappears to have her full body massage in the Ayurvedic spa. She doesn't come back for ages, having fallen asleep (again) in the suspended pods of the relaxation room.

By noon, any clouds have completely cleared, revealing a sky of intense blue. Walking down to the beach past the natural pool, studded with granite rocks and splintered with green reeds, we pass Phil the Hot Tub Host. Perfectly upright on this occasion, he is leading his clients to and from his giant, red soup bowls like a convivial cannibal. Unable to resist his charms, we book a session and are soon neck-deep in steaming water, inhaling wood-smoked aromas, the soul-cleansing sound of waves in our ears.
Whether you're soaking or reclining, walking, feasting or fishing – it's great to enjoy a romantic escape with such a healthy conscience. 'I feel like a Celtic god,' I grin through the haze from our hot tub, fully relaxed and at ease. 'Borus,' Mrs Smith whispers, proudly demonstrating she knows the name of the Celtic god of hot springs. 'Who knew our dirty weekend would be so, well, cleansing?'