The Bobbsey Twins’ Mystery on the Deep Blue Sea

The Bobbsey Twins Mystery on the Deep Blue Sea was published in 1949, one of the later additions to the original series numbering. The Bobbsey family travels by ocean liner to visit relatives, and the bulk of the book takes place aboard the ship during a transatlantic voyage. The plot is more mystery-forward than some of the earlier titles, since by the late 1940s the series had absorbed influences from Nancy Drew and the Hardy Boys, which the same publishing syndicate was producing.

The central mystery involves a series of small thefts from passengers’ staterooms, and Bert and Nan eventually identify the culprit through observation and a small piece of overheard conversation. Flossie and Freddie nearly fall overboard at least once, which by the standards of the series counts as one of the more dramatic moments. Cruise-ship life of the period is rendered with reasonable detail. A solid mid-series entry, more plotted than the early books.