Pippa Middleton hits the beach in sporty mini dress and halter-neck bikini

Ever since Pippa Middleton graced the spotlight on her sister Kate's wedding day to Prince William in 2011, royal fans have been obsessed with her athletic prowess.

Sporty Pippa, 40, has spent the last week soaking up the sunshine at the ultra-glamorous Eden Rock resort in celebrity-favourite Caribbean island, St Barths - and has brought with her £1,000 worth of designer bikinis from ViX and Heidi Klein.

As she holidays with her husband James Matthews and their three children, Arthur, five, Grace, two, and one-year-old Rose, royal fans couldn't help but notice that Pippa is looking stronger than ever as she sunbathes on the pristine white sand beaches.

In new photographs of the mother-of-three, Pippa looked incredible as she splashed around with her daughter wearing a chic printed halter-neck bikini from Heidi Klein.

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Pippa's 'Rum Point' bikini set, which retails for £225, showed off her athletic silhouette and sunkissed glow as she ran into the ocean for a cooling dip.

It's no secret that all of the Middletons have a natural affinity for health and fitness. The Princess of Wales is believed to follow a versatile and disciplined workout routine, while new father James Middleton previously joined his sister Pippa by competing in the annual Otillo Swimrun World Championships in Sweden for her 32nd birthday.

It seems Pippa doesn't hit the pause button on her workout routine, even when she's on holiday.

On Wednesday, the brunette beauty walked along the oceanfront in an Adidas x Stella McCartney court dress, suggesting she had enjoyed a morning tennis session before hitting the beach.

She paired her tennis whites with a white visor and round sunglasses, carrying a wicker beach bag with her.

Former marathon runner Pippa is notoriously sporty. Not only has she skied in the world's longest downhill race, but she's crossed the finish line at several triathlons and took part in the 50-mile ÖTILLÖ swimming and running event in Stockholm, Sweden.

"I have goals for the future and challenges I'd like to embrace so I've kept them on my bucket list to return to when the time is right, this includes the London and New York marathons, the Coast-to-Coast multi-sport event in New Zealand, the Ultra Trail du Mont Blanc MCC (the 40km race) and the Cape Town Cycle Tour," the sporty mum-of-three told running brand, HOKA.

Prior to her wedding, E! News reported that Pippa was training up to five times per week as part of an intense three-month bridal bootcamp at the upscale Grace Belgravia spa and health club in London.