John Ramsey, a young psychologist from the Bureau of Psychology (BuPsych), is trained as an electronics operator and sent on the next mission, replacing the previous officer who went insane.

Galaxy reviewer Floyd C. Gale praised Dragon in the Sea as "a dramatically fascinating story.

"[7] Anthony Boucher found the novel "as impressive in its cumulative depiction of a specialized scientific background as anything since Hal Clement's Mission of Gravity.

"[8] Spider Robinson, reviewing a mid-1970s reissue, faulted the novel's characterizations, saying "there are no real people in it, only psychological types and syndromes walking around on legs.

"[9] J. Francis McComas praised the novel in The New York Times, comparing it to Forester and Wouk and declaring, "In this fine blend of speculation and action, Mr. Herbert has created a novel that ranks with the best of modern science fiction.