Hittin' the waters for a badass jetski sesh!!

The (former?) UFC superstar was spotted out off the coast of Dalkey in Dublin fresh off his 3rd retirement announcement in 4 years on Monday ... pretty much re-enacting that iconic scene from Netflix's "Tiger King."

You know what we're talking about. All that's missing is the "Eye Of The Tiger" playing in the background.

Conor was spotted making waves on a neon jetski ... circling around an expensive-looking yacht. Smell like retirement, or just another day in the life of being a rich guy??

Now, who knows if McGregor is REALLY done fighting ... but the dude is definitely playing the part -- he's even out here eating big ass brownies.

If he's trying to send a message, he's already got Floyd Mayweather's attention ... who said Notorious is "quitting."