Shirtless Shawn Mendes Packs on PDA With Sexy Bikini-Clad Bruna Marquezine

Shawn Mendes and his girlfriend Bruna Marquezine tried to cool down at the beach ... but with all the PDA they packed on ... things got super hot!

Shawn and his gorgeous actress gal were recently snapped showing off their killer bods ... as they were all over each other in Bruna's native Brazil.

As you can see ... they were all smiles -- that is, when they were not locking lips as the waves rolled in.

This kinda thing is normal for the couple ... the singer-songwriter and the Brazilian bombshell have been snapped before showing some serious lovin' at a Brazilian beach.