If your dive site is not listed, you can add a custom location:
Select the '+' in the dive locations selection page.
Drop the pin in the correct location, or use the search bar to navigate to a different location and drop the pin there.
Use the drop pin on the map to locate the coordinates and click save.
Add a 'New Location Dive Site Title', update the coordinates manually if needed, and choose to make the custom site public or hidden.
Click 'Select this site.'
Click the back arrow button in the top left corner to see your custom dive site added to your dive log.