Split view of the Milky Way, a mountainous landscape and the underwater

To accomplish this amazing image, photographer Johannes Holzer used two cameras, a Sony A7r and Vixen Polarie Startracker to shoot the Milky Way and the mountainous landscape, a Canon 5Dm2 with an EWA Underwater case to capture the underwater view beneath a frigid German river from roughly the same perspective, finally he combined three photos together. Source