Kim Kardashian has shared her first photos to Instagram from her secret 40th birthday vacation.

On Monday morning the Keeping Up With The Kardashians star posted four pinup images while in the ocean on a white sandy beach. It has been reported she was at a private island in the Caribbean with her friends and family for a big celebration.

The beauty mogul looked sensational in a nude string bikini that made the most of her sizzling hourglass shape as she added, ‘This is 40!’

Kim had on a very small nude string bikini with mirrored wraparound sunglasses and a brown Louis Vuitton scarf on her head as she went knee deep in the crystal light blue waters on a white sand beach. Her long nails were painted electric yellow.

The Kourtney & Kim Take Miami veteran wore her long dark hair down to her bottom as she added a yellow gold ID bracelet.

The star turned 40-years-old on October 22.

The mother-of-four – she has North, Saint, Chicago and Psalm with Kanye West – did not have a big party in Los Angeles, but rather had a small get together ahead of time with her family for an E! special about her life.

Khloe, Kourtney, Kylie and Kendall were all there and even danced for her while in black outfits.

The KKW Fragrance CEO saved all the fun last week for a getaway with those closest to her.

According to PageSix, she flew some of her closest friends and relatives out to a private island to mark her milestone birthday.

But because Kim did not tag her location in her new Instagram photos, it cannot be known for sure where she is.

‘All the guests know is when to be ready to be picked up for the flight, which will leave the Los Angeles area early next week,’ a source told the outlet last week.

‘The destination is being kept strictly under wraps for privacy reasons, but that isn’t stopping everyone from speculating.’

It is believed the destination was the Caribbean. For safety, every guest was tested once for COVID-19 before the trip and again before getting on the jet.

Kim has admitted she was worried about turning 40.

When asked if she has fears about ageing, she said: ‘Every single day. We were having dinner with my mom last night for her birthday. We were talking about the same thing. It’s obviously about the wisdom. There’s a sense of calmness and wisdom you get from life.

‘But it also just sucks. There’s no easy way. [But] I would take ageing over not being here.’

And Kim also confessed to using anti-aging serums – which are typically reserved for the face – ‘all over’ her body to keep her skin fresh and looking youthful.

She admitted: ‘I always put skincare all over, I think that’s really a necessity; I put it on my legs, my arms.

‘You really have to do your neck and your chest. I might not like the scent of something, but if I feel like it’s powerful product I’ll use it all over my body.

‘I’ll just put [them] on my arms, my legs, my stomach – just use it everywhere.’

For her 40th birthday Kim had two new launches.

The siren had a new makeup collection that was more colorful than her usual choices. She wore a bikini top to jump out of a cake for that one.

And the TV favorite also sold a new SKIMS velour track suit which she used pal Paris Hilton to help her promote. The look was a flashback to 2006 when she came to fame.