This is a very unusual nature book. Most nature books are based on first-hand experience and observations (e.g. see Henry David Thoreau, Edward Abbey, Robert Finch's books). While Rachel Carson certainly studied and observed the animals she describes in this book, she did not dive under the sea, thus a lot of the narrative is based on imagination (educated imagination, no doubt). The personification of the animals -- to give them human names and describe their feelings -- is also very unique in nature books. Nonetheless, these do not detract from the scientific accuracies of Carson's descriptions. As an literary book, these in fact make the book very much more readable. Reading it is like watching a Discovery channel documentary.
I deduct one star not because of the book itself, but because of this Penguin edition. I believe there is another edition of the book with illustrations by Bob Hines, I think those illustrations are fantastic. This book contains the illustrations by Howard Frech, the same as the first edition. These illustrations are fine, but there are very few of them (I am not sure if the Penguin edition even includes all of the original Frech works). The edition with Bob Hines' illustrations are infinitely more fun to read, why did Penguin not use those? Actually, why not use both??