What kind of party do you throw for the 30th birthday of a man who had the wedding of the century just last year? For Duchess Catherine, the answer was easy -- take him to the water and throw him in.

According to The Sun in the U.K., Kate arranged an adventurous birthday bash over the weekend that included a ride for the prince in a rubber doughnut near the couple's home in Anglesey, North Wales -- despite the days' chilly temperatures.

A group of friends that included longtime pals Thomas van Straubenzee, David Jardine Paterson and Prince Harry were there to celebrate as well, indulging in a home-cooked dinner at a rented house in the evening. As Eonline.com reports, Kate did the shopping for the meal herself that day (though we're not certain about who took charge of the pots and pans).

It seems that low-key was the theme for this 30th birthday celebration, as Kate also served her husband breakfast in bed on the actual day of his birthday, June 21, before he went off to work on a search and rescue mission with the RAF, reports the U.K.'s Now Daily.

Although Kate reportedly designed a watch to give to William for his birthday, here are a few other suggestions of what she may have chosen:

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  • 1. Dance lessons. He's already got the moves but with a little more practice he could really <a href="http://www.youtube.com/watch?v=iEPTlhBmwRg" target="_hplink">Move Like Jagger</a> -- and like <a href="http://www.dailymail.co.uk/femail/article-2111338/Prince-Harry-Jamaica-Prince-dances-Bob-Marley-Diamond-Jubilee-tour-wearing-blue-shoes.html" target="_hplink">his brother Harry!</a>

  • 2. A new iPad with a fancy case to download apps (like No. 4 below). <br> 3. An iTunes playlist. To get him in the mood for dancing.

  • <a href="http://itunes.apple.com/us/app/royal-wedding-2011-keepsake/id416278975?mt=8" target="_hplink">4. Royal Wedding 2011: Keepsake Edition app. </a>

  • 5. Return to the remote cabin in Mount Kenya National Park in Lake Rutundu, <a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=1729%3Awill-and-kate-royal-tour&catid=58%3Afeature-articles&Itemid=56&limitstart=2" target="_hplink">Kenya, where Will proposed to his princess. </a>

  • 6. Return to St. Andrews University for a night in the dorm, <a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=1729:will-and-kate-royal-tour&catid=58:feature-articles&Itemid=56 class=" target="_hplink">where the Royal lovebirds first met in 2001. </a>

  • 7.<a href="http://www.themacallan.com/home.aspx" target="_hplink">Macallan 30 Year Old Fine Oak Scotch</a> -- a legendary Single Malt fit for a Prince.

  • 8. More boxer-briefs for her man, like <a href="http://www.vanityfair.com/online/daily/2012/02/royal-watch-kate-middleton-duchess-cambridge-valentines-day" target="_hplink">she did on Valentine's</a>.

  • 9. A portrait of herself. Who wouldn't want a portrait of a beautiful princess?

  • 10. DVDs -- may we recommend <a href="http://www.imdb.com/title/tt0332280/" target="_hplink">The Notebook</a> or one of <a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=3067:pop-culture-fix-april-12&catid=119:feature-articles&Itemid=259" target="_hplink">these current releases </a>-- for their Date Nights at home, <a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=3022:will-a-kate-enjoy-date-nights-curled-up-at-home&catid=117:will-and-kate&Itemid=256" target="_hplink">which they love.</a>

  • 11. <a href="http://www.tiffany.ca/Shopping/Item.aspx?fromGrid=1&sku=26021928&mcat=148208&cid=288160&search_params=s+5-p+2-c+288160-r+-x+-n+6-ri+-ni+0-t+" target="_hplink">Tiffany & Co. airplane cuff links, $275</a>, a clever accessory for pilot Will.

  • 12.<a href="http://www.harryrosen.com/store.cfm?onlineStore" target="_hplink"> Carrot & Gibbs bow ties, $75.</a> Some cheeky accessories for Will's next gala event!

  • 13. <a href="http://brandsearch.thebay.com/?gclid=CKjLken-5q8CFcK8KgodLC3Izw" target="_hplink">Fulton Kensington umbrella, $45.</a> Fulton holds a royal warrant to supply the Windsors and Cambridges with brollies. (<a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=3077:look-will-a-kate-at-premiere-of-african-cats-in-london&catid=117:will-and-kate&Itemid=256" target="_hplink">Will will be caught in the rain in style next time!) </a>

  • 14. <a href="http://oliverspencertoronto.com/" target="_hplink">Filson duffle bag</a>, a rugged bag for Will to tote on his next military expedition!

  • 15. <a href="http://www.harryrosen.com/eng/products/casual/shortsswimwear/ikb_turtle_moorea_shorts?53371562" target="_hplink">Vilebrequin swim trunks</a>, $245. For the royal couple's next exotic getaway!

  • 16. <a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=2144:will-a-kate-get-the-weird-doll-treament&catid=117:will-and-kate&Itemid=256" target="_hplink">Their own Will and Kate dolls</a> -- or <a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=2539:watch-will-a-kate-get-pop-art-treatment&catid=117:will-and-kate&Itemid=256" target="_hplink">pop art </a>of themselves.

  • 17. A baby.<a href="http://www.2forcouples.com/index.php?option=com_content&view=article&id=3081:look-will-a-kate-with-a-baby-today&catid=117:will-and-kate&Itemid=256" target="_hplink"> Will looks ready for one! </a>