This product is 290 pages long. It starts with a cover, credits, and ToC. (4 pages)
Chapter 1 – Undersea Basics (22 pages)
It starts with a IC introduction explaining what has happened and why 99% of the world is covered in water now. It moves onto a OOC explaining how and why the book was made, followed with advice on using it and common terms in the book. Next it gets into the environments of the sea. The different zones in the ocean, close to land, far from it. How deep one is from the surface, including how much light there is, the effects of the tides etc It gets very in depth and covers everything very well.
Next they get into buoyancy, it goes into great deal of the effects this has on characters and creatures under the sea. It also gets into drag effects of pulling a object or person along underwater. Followed by the effects of pressure has on living things. Next is current's riptides, and undertow, swimming speeds, terrain above water and at the bottom of the ocean. I don't know how realistic all of it is, but it is well written and seems like it would work very well and makes sense.
Next it gets into perils like poisons, diseases, blood in the water drawing sharks, water conditions like murk or whirlpools etc. It ends with a short section on undersea combat, with some differences. Like it being a 3D environment.
Chapter 2 – Undersea Races (20 pages)
This chapter details the undersea races one can play in a undersea campaign. They are all done in enough depth and detail to easily pick one up and start playing with them, giving you everything you need just like the main races in Pathfinder core rule book. The are broken up be species type and then by individual race. It finishes with a whole host of half bread combinations. Since many of them are egg laying races it is far easy to get cross breeding as any male can fertilize the eggs.
Chapter 3 – Undersea Classes (34 pages)
At first it talks about how you can adapt the existing Pathfinder classes to use in the game, including the APG classes. Some are pretty minor changes some are a bit more complex. It also introduces two more domains, undersea Flora and Steam domains. It also has a table of 27 deities, domains weapons etc, more details in chapter 7. The druid has 18 new animal companion options. There is several new Eidolon evolutions to choose from. Plus 12 more familiars for the witch and wizard.
Next it introduces three new classes. They replace the niche of some of the existing classes in new and interesting ways. There is nothing stopping you from using both classes in the same game though.
Kahuna – replaces the Druid
Mariner – replaces the ranger
Siren – replaces the Bard
Next it gets into PrC's and which ones fit and what you need to change if anything and the ones that don't. It also includes three new PrC's as well.
Beach Comber – They go up on some of the little land left and spend time there.
Glimmerkeepers – Honestly to hard to explain but very cool.
SeaWitch – a PrC for the new Siren class.
Chapter 4 – Aquatic Skills and Feats (14 pages)
It starts off talking about all the skills that are different and how they are different. Next it moves onto existing feats that need to be tweaked and what they do now to fit. Next it introduces 45 new undersea flavored feats that all fit very well.
Chapter 5 – Money and Equipment (20 pages)
First it gets into the new money system, since most metals tarnish or rust underwater it makes sense. They use small shells, gold, pearls and such. Now on the shells they really should have made it clear they had to have stamps to make them valuable or people could just go kill the creatures and take their shells for money.
It follows this with a section on weapons, armor and undersea gears. There is simply way to much to list or even high light. They did a good job with the gear for the most part. Other than a few minor issues like Spiked Chain which honestly just would not work underwater. It even has a section on sailing ships. There is several new weapons, armor and a couple of dozen new gear items, not to mention many of the old stuff tweaked to fit the setting.
Chapter 6 – Magic of the Sea (34 pages)
It starts off talking about how spells will work differently underwater. It is followed by a table of aquatic material components in place of the existing ones. I thought that was very cool as some stuff just wouldn't exist underwater. Next it has a chart of spells and their new names, while not needed it was very cool and makes sense. I mean no one would call a fireball and fireball underwater, instead it is mageboil as it makes the water boil instead.
Next it details all the new spells and spells that have changed such as fireball to mageboil. I tried counting but I lost count. There is around a 120-130 spells, I am honestly unsure how many are new and how many are altered. At a glance I would say close to 50/50. It ends with 9 new magic items and a few new magic item properties.
Chapter 7 – The Cerulean Seas (25 pages)
This section gets into the campaign setting, it has the gods, cities, etc, it is a campaign gazetteer for the default setting of the book.
Chapter 8 – Mastering the Sea (10 pages)
This is the game master section of the book on how to run games underwater. It gets into greater detail of some of the previous stuff like buoyancy etc. About how to find depth tolerances for creatures, by what they are. The most interesting section is on 3D combat and how to make your own 3d combat mat to use with mini's if you like. It ends with a section on how the planes interact with the sea.
Chapter 9 – Cerulean Sea Bestiary (72 pages)
This chapter is just a monster bestiary for the setting but also a great one for anyone that ever wants to run a undersea adventure. There is 95 new monsters including new sound based dragons which all looked different and where really interesting. Many had more than one stat block like the dragons. There was also 5 new templates.
Appendices (6 pages)
There is a few Appendix in this section, monsters listed by CR, pronunciation guide, index of tables and index of art.
It ends with a OGL, 2 page character sheet, 4 cardboard mini's, hex sheets to make the 3D battle map with, a full page map, indepth index and back cover. (17 pages)
Closing thoughts. This is a very well written, very pretty book about undersea campaigns. The art work is mostly color and very good high quality art. The editing, layout and production values was top notch. Simply put if you ever wanted a book to help you run a undersea campaign THIS is the book to get. Even if you don't want to, this would be a great tool if you ever wanted to just run some adventures underwater.
Now the book is not perfect, there is a few minor issues where and there with it, like the spiked chain or the shells I mentioned. But most of them are pretty minor issues. My only real critic is honestly the price. I understand Alluria publishing is a small company and art is very expensive, after seeing the art in this book I am sure they spent a bundle on the art budget. But it is a bit high priced at 29.99 for a PDF. If that was the print price I would say fair price, for a PDF though? I felt a tad high. So whats my rating? Well just on the book it is easily a 5 star product, with the price I would say a 4.5 star. I know the price is a little high but I don't think you will be disappointed picking this up, if you find undersea adventures interesting at all.