Orlando Bloom Snorkels With Son and Bikini Babe

Orlando Bloom is meeting some of the locals over in Italy ... but we're talking about life under the sea ... 'cause he went snorkeling with his son, and a very cheeky mystery woman.

The "Pirates of the Caribbean" star enjoyed a snorkel session Sunday ... with his son Flynn and a stunning woman in a skimpy bikini. No whales in Italian waters, but plenty of whale tails on this occasion.

Orlando's snorkeling outing appears to be part of his co-parenting yacht adventure with his ex Katy Perry ... on the same day, they were spotted on a mega yacht with Jeff Bezos and Lauren Sanchez Bezos in Capri.

Flynn here is from Orlando's previous marriage to Miranda Kerr ... and Orlando's reps say he's going to co-parent his 4-year-old daughter Daisy with Katy after their recent split.

So far, the co-parenting thing is off to a great start ... though it helps to be on a yacht cruising the Italian coast.