The Apple Watch has a secret port tucked under where the strap connects to the body of the watch. This port is what Apple calls the "diagnostics port."

Fortunately, however, the port can be used for more than simply transmitting data in the event of troubleshooting. In fact, this port is a potential gold mine for Apple Watch accessory creators.

One of the biggest complaints about the Apple Watch, besides its seemingly slow performance, is the fact that its battery life won't give users more than a day of use. One accessory creator, called Reserve Strap, has essentially made a strap for the device that comes with a small battery inside of it, designed to charge the Apple Watch without users even having to take off the device. This almost means that the Apple Watch will have a second, removable battery. Users could purchase more than one of these straps, extending the life of the device for as long as they want, as long as they are able to carry around extra straps.

It's important to mention that Apple designed the port to be inaccessible by users, and while the Reserve Strap includes a tool for users to access it, this will likely void the warranty of the device.

This port could be used for any number of other things. Companies could develop straps with extra fitness tracking sensors, enabling the sports-minded to track more than the Apple Watch currently allows. This might require some software tweaks, also likely voiding the warranty of the device, but hey, if you're going to void it anyway, then why not?

It is unknown why exactly Apple is not talking about this port and why it won't allow users to access it, and the company is likely not too happy about the fact that developers and accessory creators are using it to their advantage; we might even see the company take steps to stop these companies from creating accessories that use the port. If Apple were to open up access to the port and offer developers ways to create accessories for the device, it could potentially give the device far more use than it already has. Such a move, however, is unlikely for the likes of Apple, which likes to keep things as closed and close to its chest as possible, especially considering the fact that Apple is not currently selling any accessories that make use of the port.