The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Derek Trauger & Associates:
Dive Spots is a database-driven application that provides the fastest way to locate dive spots, obstructions, and wrecks. Dive Spots provides an easy to use interface that places an ever growing database of over 21,000 dive spots, obstructions, and wrecks at your fingertips. With ease Dive Spots will provide a list of possible dive locations in proximity to your current location. The proximity and number of results can be configured to fine tune the results of your search. Diving away from your current location and need to know what dive spots are close to your destination? No problem. Simply enter the desired location's zip code or select a city and Dive Spots will provide you a list of possible locations. How to get there? Once a dive spot of interest is located its location can be fed to the built-in Maps application to obtain directions. Currently Dive Spots provides dive spots, obstructions, and wrecks for the United States, Canada, the United Kingdom and Australia. Dive spots, obstructions, and wreck locations for additional countries may be added at a later date. Dive Spots requires the iPhone OS 3.0 and an active WiFi or Cellular connection to run.