I found Marine Biology by Castro to be a fairly good introductory textbook to marine biology. The reading is not too technically difficult that an average high schooler could comprehend most of what is said without becoming lost in science talk. There are plenty of pictures and diagrams to supplement the reading and make the pages appealing to the eye without boring you to death. However, as most academic textbooks go, reading alone is almost never enough to fully understand the material. I used this book as part of an introduction to marine biology course and found it to be very helpful to read before lectures. It can be a little dry at times and hardly goes into full detail of topics, but being an introductory book, it fully met the needs of my course. Overall, it's a good textbook that I'd recommend to someone taking an introductory course to marine biology.

This book when purchased NEW is shrinkwrapped and has the ISBN 0-07-293356-9. The shrinkwrapped package contains the Marine Biology textbook (ISBN 0-07-250934-1) which contains "The Premium McGraw-Hill Online Resources" access code (ISBN 0-0-250935-X). If you are buying a used book keep in mind that the online access code may only be used once and is not transferable, so if any of the previous owners have used the code it will not work for you. If your instructor uses Blackboard or WebCT, you may NEED a valid access code. A new access codes may be purchased from the McGraw-Hill "Premium" Site for $12 if you get stuck with a used book without a valid OLC code.

The book is great, I highly recommend it to anybody interested in the subject. For instructors though, I feel that this book based on the length and the number of chapters is probably better suited for classes on the Semester system (16 weeks) rather than those on the Term system (11 weeks.)