One year after 12 boys were incredibly rescued from a flooded Thai cave, a hero diver has returned to the site and found haunting messages left by the kids.

Mikko Paasi, 44, was stunned to find carvings spelling out children's names and the words "lost boys" after digging his way into the dark chamber where the youngsters were found.

Mikko was one of more than 90 divers - including seven Brits - who saved the kids and their football coach after a shock monsoon trapped them inside the cave for an agonizing 18 days last summer.

CLICK HERE FOR MORE FROM THE SUN

THAI CAVE BOYS WERE ACTUALLY HANDCUFFED, HEAVILY SEDATED DURING DRAMATIC RESCUE, NEW BOOK CLAIMS

It turned out to be one of the most dangerous rescues in history.

Now, as Thailand marks one year since the last of the boys was brought out alive, Mikko exclusively tells Sun Online how he helped save the youngsters against all odds - and how he has been back to the site and uncovered hidden carvings and other lost relics.

THAI SOCCER TEAM GIVEN DRUGS TO MAKE THEM 'NOT STRESSED' DURING CAVE RESCUE, OFFICIALS SAY

"It was intense," he says.

"We found a boy had carved his Facebook address on the wall. We found markings in Thai like '13 boys lost'... and then there were dates like June 26."

CLICK HERE FOR THE FOX NEWS APP

This story originally appeared in The Sun. For more from The Sun, click here.