Hudson Williams knows all about bringing the heat ... and the "Heated Rivalry" star is putting his skills to work over in Greece ... packing on the PDA with his longtime girlfriend.

Check out the photos ... a shirtless Hudson is kissing all over his tattoo artist girlfriend Katelyn Larson as they play in the waves at the iconic Nammos Beach on Psarou, a Greek island.

It wasn't just kissing ... Hudson and Katleyn hugged and held their bodies close ... super romantic!!!

Hudson looks like a hunk with his slicked-back dark hair, and Katelyn is easy on the eyes in a polka dot bikini.

When they weren't kissing or hugging, Hudson was squeezing a lime into a drink and sipping the concoction in the waist-deep water. Ah, refreshing.

Looks like it's all Greek to Hudson and Katelyn.

It's summer ... who needs a hockey rink?!?