BERNICE BOUIE DONALD, Circuit Judge. Mammoth Cave National Park in Kentucky is home to the world’s longest known cave system, spanning more than 400 miles.1 It is also where Jason Zabel committed abusive sexual contact against a female National Park Service employee—a crime for which he pled guilty and received a sentence of 18 months’ imprisonment, followed by a life term of supervised release. On appeal, Zabel argues that the district court erred in denying his pre-guilty-plea motion to suppress incriminating statements he made to park rangers and that his sentence—both the term of incarceration and lifetime supervision—was procedurally and substantively unreasonable. He also contends that his statutory maximum term of supervised release violates the Eighth Amendment’s prohibition against cruel and unusual punishment. For the following reasons, we affirm the district court’s judgment and sentence.