This snorkelers’ guide to the most common invertebrates and other commonly seen water inhabitants in Hawai‘i includes 374 gorgeous photos together with extensive notes for each. All content is by an experts in the field: Keoki and Yuko Stender, and snorkeling guidebook authors, Judy and Mel Malinowski. As a bonus, links to underwater videos by Keller Laros, Rob Whitton, Mel Malinowski and others are provided. This app provides a beautiful and convenient way to look up critters you have seen, or would like to see. It is fast and easy to use. Because of the large number of high quality pictures the size is 160 MB, thus you must download it via WiFi or better (not cellular). Users can view an indexed list of 35 families with a thumbnail of a typical member of that family. Tap on a family to see the critters from that family, with a thumbnail picture, the common name, and the scientific name. Tap on that critter to see a detail view, with large picture, and detailed notes. Tap on the picture to enlarge it to full screen. Tap again to return. Tap on an add button to add to personal Favorites list. Tap on All Critters to display a complete indexed alphabetical list of 374 critters, with thumbnail pictures, common name and scientific name. Tap on one row to see details for that critter. Tap on Slideshow to see a full screen slideshow of sharp, colorful pictures in random order with names shown. Tap again to pause. Swipe to go to the detail view with notes. Tap to return to the slideshow, or tap twice to exit. Tap on Favorites to view a list of personal 'Favorites', which can be added to, edited, or deleted. Tap on Books to view other resources available from the authors, including an extensive website and snorkeling site guidebooks. An 'i' button on the top right of the front page leads to complete instructions for the app. The app is so intuitive, however, that this is unlikely to be needed. Other apps in the Reef Fish series include Reef Fish Hawaii, Mauna Lani (free), and Reef Fish Florida & Caribbean.