SuperView is GoPro's name for its widest field of view, or FOV, available when shooting video.1 GoPro calls it "the world’s most immersive field of view."2 It's also not the same thing as SuperPhoto, which is GoPro's name for some photo enhancement features first launched in the HERO7 Black.
The default field of view for shooting video with GoPro cameras is known as Wide. It has that distinctive fisheye look that can give an immersive feel, and it's the perspective we're most used to when we see GoPro footage.
The SuperView is an even wider and more distorted perspective. The most obvious change is that it milks just a little more from each side. To include that extra information, it squashes the rest of the frame a bit more.
What it's actually doing is stretching a 4:3 aspect ratio capture into a viewport that has an aspect ratio of 16:9. But it's not just vertical squishing--it's also using more of the available sensor data on each side.
It's not available on every camera, and even on cameras that do have it, it's not available in every resolution/framerate combination. On the HERO7 Black, for example, it's not available on the highest framerates for each resolution (you can find details on the table at the bottom of this page).
Here's a practical example of what it looks like compared with the default Wide FOV. The left image is the standard Wide FOV. The right is the SuperView FOV. These are screen grabs from footage taken on the HERO7 Black with the HyperSmooth stabilization turned off (the stabilization crops the frame slightly).
Here's another example, this time shot on a HERO6 Black:
[caption id="attachment_20567" align="aligncenter" width="678"] GoPro HERO6 Black Video FOV: Wide[/caption]
[caption id="attachment_20566" align="aligncenter" width="678"] GoPro HERO6 Black Video FOV: Superview[/caption]
And another, again with the HERO7 Black:
When to Use SuperView
There are no hard and fast rules on which field of view to use when--that's very much a creative decision--but the extra leeway with SuperView is particularly well suited to two common situations: when it's not practical to compose the shot precisely and want to make sure that your subject remains in the frame (ie. a simpler version of the idea of overcapture used on the Fusion), and when you're in a tight space where you're trying to capture as much of the surroundings as possible. GoPro suggests that it's good for body and gear-mounted shots, which falls within those scenarios.
What it's not especially good for is any time that the highly distorted and compressed look is going to appear strange. So you wouldn't normally use it for standard people shots, for example, where it's going to distort their face and body in a distracting way.