Nearly as good as the GoPro Hero 7 Black in features and video quality, but it's just $220 with a waterproof dive housing included. Its electronic image stabilization isn't quite as good as GoPro's HyperSmooth, but it's definitely better than nothing. You also get shooting options like 4K video at 60 fps (with image stabilization at 30 fps), slow-motion video at 1080p at 120 fps or 720p at 240 fps, time-lapse photos and videos, live streaming and raw photo capture. You don't get anything more than the camera, a battery, the housing and charging and external mic cables, but if your main concern is getting good photos and video for less than a GoPro, this is a safe bet. Read more about the Yi 4K Plus.
Which is the best GoPro?
The GoPro Hero 5 is a fantastic underwater camera. However, there is a catch. The device cannot submerge on its own. Rather, it requires a Super Suit Dive Housing (also from GoPro) to get wet. Even so, that accessory turns it into one of the best diving cameras around. The device is able to go down to 196 feet and comes with a bright 2-inch touchscreen display that is easy to use while swimming. The ultra-wide angle lens, 4k recording capabilities, and 12MP image resolution bring it all together.
What is the best knock off GoPro?
The reason I ask what you will be using it for is to determine which set of features you need. If you're going to be using it for simpler activities, don't go all out for a Black edition with a 60fps, 1080p cam (all HERO3's are 1080p, anyways). The reason the Black Edition is so expensive is because of the crazy quality it has, and if you're using it for a more simple basis I wouldn't worry about the difference. The Silver or even White is perfectly fine for you. The main difference between these two is the white's camera has a 5 megapixels with 3fps burst while the silver is 11 megapixels with a 10 fps burst -- is that worth $100 to you?
What GoPros are compatible with the app?
You get many of the same shooting modes you'd find on a GoPro device, such as time-lapse photos and videos and slow motion footage at 1080p at 240 fps, and there's even a Drive mode so you can use it as a dash cam when plugged into your car, automatically turning on when you start your car and off when you stop it. It's not waterproof on its own, but a dive housing is included as well as several mounts, two batteries and a charger that simultaneously powers up both packs. It also has built-in Wi-Fi so you can connect to a smartphone and use an app to control the camera and transfer your shots for sharing.