The DARPA SubT Challenge: A robot triathlon

One of the biggest urban legends growing up in New York City were rumors about alligators living in the sewers. This myth even inspired a popular children's book called "The Great Escape: Or, The Sewer Story," with illustrations of reptiles crawling out of apartment toilets. To this day, city dwellers anxiously look at manholes wondering what lurks below. This curiosity was shared last month by the US Defense Department with its appeal for access to commercial underground complexes. The US military's research arm, DARPA, launched the Subterranean (or SubT) Challenge in 2017 with the expressed goal of developing systems that enhance "situational awareness capabilities" for underground missions.