Volumes ‐ Effect volumes
Most of the sections here in the NH docs are one-to-one with the corresponding unity components, so you should use those as reference.
In fact, you should probably just use NH to make the volumes, unless it's more convenient to do it in unity or you need that extra bit of customization.
EffectVolumes use OWTriggerVolumes, so much of the process is the same as creating OWTriggerVolumes.
Add the EffectVolume subclass after adding the OWTriggerVolume.
For documentation on layer and priority, see the NH docs for layer and priority
ForceVolumes accelerate objects with a ForceDetector component (like the player) in a certain direction.
They usually have obvious parameters for changing how the force acts. For example, in the screenshot, the DirectionalForceVolume has properties for the direction that the force will push things in, and the magnitude that decides how strong the force will be.
Alignment means that the pushed object will rotate to align with the direction of the force. It has its own priority.
Inheritable makes it so that the volume passes on forces applied to its parent body. For example, the Zero-G Cave volume has this enabled, so the player is still affected by the planet's orbit instead of truly being acted on by zero force.
Like forces, FluidVolumes accelerate an object with a FluidDetector component (like the player) in a certain direction. However, they also exhibit drag (the strength of which is controlled by the "density" property) and can apply an angular acceleration (making the object spin).
Similar to ForceVolumes, there are properties for direction and magnitude.
Different fluid types have various effects. For example, the AIR type doesn't muffle audio and plays a wind sound if the player is moving through the volume fast enough.
See NH docs for more info.
The above image uses trigger volume override to set its associated trigger volume, but normally it's enough to put the OWTriggerVolume component on the same GameObject as the AudioVolume.
See NH docs for more info.
As said at the top of this page, please see the NH docs for information on the various volume types and their properties.