Kate Middleton and Prince William
Kate Middleton took part in a high-risk activity during their family holiday trip in Mustique. Pictured: Middleton arrives at the centre and also have Lunch with the Clients, and cooking and making Lunch in Barnsley, England on Nov. 14, 2018. Getty Images/Charlotte Graham

Kate Middleton took part in a high-risk activity during their family holiday trip.

Earlier this year, the Duke and Duchess of Cambridge visited Mustique for their annual vacation. Prince William and Middleton traveled with their three children, 5-year-old Prince George, 3-year-old Princess Charlotte and 6-month-old Prince Louis. Middleton's parents were also with them.

Kara Godfrey, a journalist for Express, recently revealed that during the trip, adventurous Middleton went training for her advanced scuba diving test. They could go to as deep as 98 feet, and Middleton would have undertaken five deep dives and navigation dives to pass the test.

Deep sea divers carry emergency equipment like knives and compasses for defense and to escape a treacherous situation. However, this activity is extremely dangerous.

One of the risks that come with the water activity is the "bends" which happens when nitrogen bubbles form in the blood if the driver rises to the surface too quickly. Despite the risks, Prince William and Middleton are both fans of the activity and even hope that their children would inherit their love for water sports.

"Scuba diving really has opened my eyes not only to many extraordinary sights but also to the responsibilities that we have as guardians of the underwater world," Prince William said.

During the same trip, the Duke and Duchess of Cambridge were also seen in a rare wild night out at the famous Basil's Bar. According to onlookers, the royal couple attended "on the early side" of the party. "They were there for the cocktails segment and kept it rather classy," the source said.

Since Mustique is an exclusive island that offers guests complete privacy, Prince William and Middleton blend with the tourists. They were seen dancing with Middleton wearing a headdress and a skirt.

In related news, body language expert Judi James noticed that Prince William and Middleton have become more tactile. According to her, this could be Prince Harry and Meghan Markle's influence.

"It's unusual to see William taking the lead in terms of public touch rituals with Kate, but on Remembrance Sunday he performed this back-touch ritual, even splaying his thumb out to signal a rather protective form of affection," James said. "Now that they are less obsessed with keeping to their more formal, non-tactile 'rules' they tend to look happier and more relaxed together too."