Winnie Harlow and Kyle Kuzma are making sure their birthday festivities don't come and go in just a day -- the engaged couple is keeping the vibes going on a fancy yacht in the Mediterranean!!
The 30-year-old NBA hooper -- whose special day was on the 24th -- was spotted out on the water with his model fiancée this week ... and it sure seemed like a joint celebration, as she blew out 31 candles on the 27th.
The pair appeared to be as happy as they could be aboard the boat with friends near Formentera .