Kate Middleton's hidden hobby - but she always wears one key piece of jewellery to do it

is one of the most famous women in the - but she has found a hobby that allows her to go incognito.

Kate and her husband were captured on camera enjoying one of their favourite pastimes during a visit to the Caribbean in 2022. And even the most dedicated royal watchers would have struggled to recognise the couple. At the time, William and Kate were on a week-long tour to Belize, Jamaica and the Bahamas to commemorate the , marking her 70th year on the throne.

Despite their jam-packed schedule, they were able to slip away unnoticed during the second day of their to enjoy a previously unannounced trip. William and Kate went snorkelling and diving with 2021 Prize Winner Coral Vita to better understand their project on farming and planting coral in the Bahamas.

In a video shared on their official social media pages and taken by , the royals were seen jumping off the back of a boat, swimming underwater, and giving each other the 'okay' hand signal, as they took in the local marine life.

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Kate looks unrecognisable in the clip, wearing a wetsuit, flippers, goggles and a snorkel, and with her long hair tied back in a ponytail. But there was one tell-tale sign that gave away her identity. To the surprise of royal fans, the Princess was still wearing her priceless sapphire engagement ring, which once belonged to the late , as she explored the reef with her husband.

boasts a huge oval Ceylon sapphire that weighs 12 carats. The blue stone is surrounded by 14 solitaire diamonds and set in 18-karat white gold. William presented it to Kate when he popped the question back in 2010.

"It's my mother's engagement ring, so I thought it was quite nice because obviously, she's not going to be around to share in any of the fun and excitement of all this," Prince William said in . "This is my way of keeping her sort of close to it all." He also told reporters of the ring: "It's very special to me. As Kate's very special to me now, it was right to put the two together."

It was long believed that when the ring came into Kate's possession, she had it altered in order to make it fit her finger perfectly. However, while on a trip to Wales, . "It's the same ring and it was exactly the same size when I tried it on," Kate told one well-wisher, who complimented her on the jewel.

She continued: "I'm honoured to wear it, I never sadly got to meet her. And also now with the children and grandchildren, I think . She'd be absolutely brilliant, we miss her every day."