Kim Kardashian in Bikini on a Yacht in Miami

Kim Kardashian stretches back and lets out a huge yawn while basking in the Miami sun on a luxury yacht.

The American socialite made relaxing look like tiring work as she reclined in her lounger, leaving little to the imagination in a tiny peach bikini.

The 29-year-old reality star was joined by her sister Kourtney, 30, who covered up in a loose white top, and cooled down by sipping on a refreshing orange drink.

Usually based in Los Angeles, Kourtney and Khloe relocated to Miami earlier this month to film a second series of their spin-off reality TV show Kourtney And Khloe Take Miami.

Before boarding the yacht yesterday, the pair were seen leaving a local gym following a workout session.

While Kim insists she is happy in her current relationship with American football player Reggie Bush, she did admit feeling broody during Kourtney's pregnancy last year.

She said: 'I want a baby!!!! OK, so maybe not right now, but I can't wait to be an aunt.'

Kim was spotted gushing over her three-month-old nephew Mason Dash Disick as she shopped with his mother Kourtney on Friday.

Showing off her figure in a pair of tight jeans and fringed waistcoat, Kim pulled faces and lavished attention on her cute little relative.

Kim was shopping for a new car in a Maserati showroom in Miami, but found herself distracted by her nephew, who was wearing a blue babygrow.

Given pictures of baby Mason, it is clear he takes after the Kardashian family looks-wise, rather than his father Scott Disick.

In a recent chat with the Celebrity Baby Blog website, Kourtney admitted her son looks like her younger brother Rob, who also appears in Keeping Up With The Kardashians