Justin and Hailey Bieber are enjoying some of their recent windfall ... because they're on vacation on a Spanish isle ... and they look super happy.

The parents snuck off Tuesday for a date night in Mallorca, enjoying dinner and a sunset along the water ... and there was plenty of PDA.

Justin and Hailey held hands as they walked into a restaurant ... and after their meal, they plopped down on a patch of coastline and Hailey started rubbing Justin's back. A tender moment, for sure.

No sign of baby Jack Blues here ... so it looks like Justin and Hailey got to enjoy some kid-free fun ... which is always important for first-time parents. Besides, Justin had Jack in the studio just the other day.

Justin and Hailey are definitely enjoying their summer ... we've also seen them at concerts, at lakes and on pickleball courts.