Join Karst Underwater Research (KUR) divers Charlie Roberson and Jon Bernot at TEKDiveUSA.2018 for a discussion of their ongoing exploration of the Falmouth-Cathedral and Lineater cave systems. These twin but so far unconnected cave systems have lived up to their challenging reputations and world-record history. In 2016, Jon and Charlie set a new world record for penetration in an underwater cave at 8,208 m / 26,930 ft in the Falmouth-Cathedral system. This year, KUR has focused its exploration efforts on Lineater, where the penetration is currently 7,065 m / 21,194 ft. The long distances and often poor conditions in these systems present unique logistical challenges for exploration.