Scheana Shay is standing by her hubby, Brock Davies, as the two reality TV stars recently hit Puerto Rico for an Ironman triathlon!

The series of challenges -- a 1.2-mile swim, a 56-mile bike ride and a 13.1-mile run -- were exactly half the length of a traditional Ironman challenge ... mad respect, Brock!

Cheerin' on her man, The "Vanderpump Rules" alum planted a smooch after her bulky baby daddy completed one of his races!

Swim, bike, run ... and then have some fun with our photo gallery above -- see Brock and Scheana take Puerto Rico!

By the way, Brock ain't the only 'VPR' star with a smokin' hot bod ... test your reality TV knowledge and see if you can guess each hot shot!