The Sea Raiders sea monsters include Scylla and Charybdis of Greek mythology, and the kraken of medieval times which is thought to have been a giant squid. Previous fictional encounters with giant squids are described in chapter 59 of Herman Melville's "Moby-Dick" of 1851, and in Jules Verne's "Twenty Thousand Leagues Under the Sea" of 1870. The narrator describes a recent period when a new sort of giant squid, a species named "Haploteuthis ferox", became known. (This fictitious name can be compared with the genus name "Architeuthis" of the giant squid.) As a part of the survey of the period, including early encounters
Twenty Thousand Leagues Under the Sea of underwater breathing apparatus designed by Benoit Rouquayrol and Auguste Denayrouze in 1865. They designed a diving set with a backpack spherical air tank that supplied air through the first known demand regulator. The diver still walked on the seabed and did not swim. This set was called an "aérophore" (Greek for "air-carrier"). Air pressure tanks made with the technology of the time could only hold 30 atmospheres, and the diver had to be surface supplied; the tank was for bailout. The durations of 6 to 8 hours on a tankful without external supply recorded for the Rouquayrol set in