The Dragon in the Sea (1956), also known as Under Pressure from its serialization, is a novel by Frank Herbert. It was first serialized in Astounding magazine from 1955 to 1956, then reworked and published as a standalone novel in 1956. A 1961 2nd printing of the Avon paperback, catalog # G-1092, was titled 21st Century Sub with the previous title in parentheses, and a short 36 page version of the novel was later collected in Eye. It is usually classified as a psychological novel. Source: Wikipedia (en)