Rihanna & A$AP Rocky Living It Up Together on Vacation in Barbados

A$AP Rocky and Rihanna are doing the ultimate love bird thing that an expecting couple could while on vacation -- soon-to-be Mama Bear looking on as dad takes on Mother Nature.

The singer/fashion mogul was taking in the sights Tuesday down in her native Barbados -- notably, the sight of her baby daddy ripping and roaring through the ocean just outside their vacay home while mounted on a jet ski.

Check it out ... Rihanna is surrounded by some friends/fam, checking in on A$AP with a pair of binoculars as he navigates the choppy waters solo. Seems like she was impressed by what she was seeing, and likewise ... he was pretty happy too. Each of them were all smiles.

Of course, RiRi is heavily pregnant -- it looks like she could pop any day now -- so she definitely wasn't going to join on this particular excursion.

No worries, because A$AP was able to manage just fine on his own ... and before long, he reunited with his lady on land and they headed back inside together. If you didn't believe your eyes before this weekend, you can believe this -- they're very much together.

We'd already been told there was no truth to them splitting over alleged cheating -- it was nothing more than a Twitter rumor that took off like wildfire -- but the proof is in the pudding now that they're in each other's company again, looking super boo'd up, per usual.

Like we said, the future parents aren't just putting on a united front in paradise ... they very much are a united front, for realsies.