This guide can be used in the field and away from an Internet connection. For most devices though, do not try to use it underwater. Identify all the amazing things you have seen once you are back in the boat or on dry land.
The guide has particularly good coverage of fish. Other categories of species have less complete descriptions, though all species with Sydney-specific records in the Atlas of Living Australia have been included.
If you have images or information about species with poor descriptions in this guide, please consider making a contribution via the Gaia Guide website (http://www.gaiaguide.info/).
The 17+ rating is required because many of the descriptions include links to other websites, allowing unrestricted web access.