Despite making a record 128 appearances for Portugal, he has yet to score in its two games so far in the competition, and even missed a penalty against Austria on Saturday.
He has also endured criticism for accusing Iceland of having a "small mentality" following Portugal's draw with the team in its opening game.
But his frustration appeared to really come to come to a head this morning when a CMTV reporter approached the Portugal side walking from its hotel in Lyons.
Watch Ronaldo throwing a reporter's microphone into the lake:
Speaking yesterday to the BBC, Portugal midfielder Adrien Silva said Ronaldo would rise above pressure:
"There's a lot of people criticising. I don't think it's going to hurt him. He's more than used to it. He does everything he can to get us the best result."
Vitor Hugo Alvarenga, a journalist for website Mais Futebol added that Ronaldo was becoming a different kind of player, and that would incur growing pains:
"As the years go by and age gets to him, besides the incredible amount of matches he plays, Cristiano Ronaldo is converting himself to a pure finisher," he said. "But he does not want to play as a traditional striker."
Portugal is currently joint second with Iceland in Group F. If Portugal loses to Hungary this evening and Iceland gets at least a point from Austria, Portugal will be out of Euro 2016.