(CNN) Sen. Susan Collins offered a deeply personal view of the late Sen. John McCain on Sunday, saying that she's going to "miss the fact that he was so much fun," as well as his humor and his mentorship in the Senate.

Appearing on CNN's "State of the Union," Collins, a Republican from Maine, shared fond memories of the Arizona Republican, who died on Saturday at the age of 81, leaving behind a long legacy of public service.

"I'm going to miss the fact that he was so much fun," Collins told CNN's Jake Tapper. "He had a great sense of humor. And I traveled extensively with him and saw that firsthand."

"His capacity to learn and his insatiable curiosity were extraordinary," Collins added. "So, I'll miss that as well. But, frankly, I will miss how much fun he was, and how much I learned from him. And he leaves a big hole in my heart."

Collins said that she took several trips with McCain, including one to Antarctica, one to his ranch in Sedona, Arizona, and a few trips to Iraq and Afghanistan in the "very early stages of the war."

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