Mystery Beneath Antarctica's Glaciers | NOVA | PBS

A twelve-foot torpedo-shaped robot named Icefin drops through boreholes to map the underside of Antarctic glaciers, reaching places no diver or submarine can go. Researchers use its footage to understand how warming ocean water is eating away at the ice from below.

Why it's free: Free on NOVA PBS's own channel; GBH first ran it on PBS Terra and NOVA republished it here.