Make all functionality available from a keyboard.
Source: WorldWideWeb Consortium Web Accessibility Initiative
Disclaimer: All of the caches in this series are nanos, and as such may not be easy to open for people who have issues with motor function. Unfortunately, it is simply too hard to place a cache that is both easily accessible by wheelchair and that won't get disturbed or removed by non-geocachers if it is large.
The previous two caches explored visual impairments. Some disabled users of the web have perfectly good visual abilities; what they lack is good motor functioning. They simply may not be able to operate a mouse.
There is a link below this paragraph that I have intentionally styled to be a very tiny circle. If you look closely, you may be able to see it. If you move your mouse around you can probably find the click target, but that would spoil the fun if you clicked on it. Here is a chance for you to learn what it is like to navigate a web page using your keyboard. Press the tab key and see what happens. Depending on whether or where you have clicked on the page, you may need to press it twice or you may need to cycle through a few clicks. You might even want to experiment with using the back tab. Once you have highlighted the Google Map link, you may press enter and you will be able to see the final coordinates.