#27 in the Tom Swift Jr. series. Grosset and Dunlap hardcover publication. Copyright 1966. Print year estimate is is 1967, since the last title on the back cover is #29 Captive Planetoid, first printed in 1967. No internal book list. Author "Victor Appleton II." Victor Appleton the first was the Stratemeyer Syndicate pen name for the initial Tom Swift series. Very good book with slight spine slant but strong binding. No tracking, tears. Black and white space lab endpapers. No writing/markings. Some light stains on the page block. In this one, Tom and Bud need to build an aquarium and stock it with deep-sea creatures in a race against time, and for that mission Tom invents a "mole mobile" geotron, a burrowing craft which bores through earth as under the ocean floor. Note to New York state residents: an 8.75% sales tax is applicable. (TSD27)