  Gravitational lensing has empowered telescopes to discover astronomical
objects that are otherwise out of reach without being highly magnified by
foreground structures. While we expect gravitational waves (GWs) from compact
binary coalescences to also experience lensing, the phenomenology of highly
magnified GWs has not been fully exploited. In this letter, we fill this gap
and explore the observational signatures of these highly magnified GWs. We find
that these signatures are robust against modeling details and can be used as
smoking-gun evidence to confirm the detection of lensing of GWs without any
electromagnetic observation. Additionally, diffraction becomes important in
some cases, which limits the maximum possible magnification and gives waveform
signatures of lensing that can only be observed by GW detectors. Even with
current-generation observatories, we are already sensitive to these highly
magnified GWs and can use them to probe the high-redshift Universe beyond the
usual horizon.
